Dominance of Plasmonic Resonant Energy Transfer over Direct Electron Transfer in Substantially Enhanced Water Oxidation Activity of BiVO4 by Shape‐Controlled Au Nanoparticles

The performance of plasmonic Au nanostructure/metal oxide heterointerface shows great promise in enhancing photoactivity, due to its ability to confine light to the small volume inside the semiconductor and modify the interfacial electronic band structure. While the shape control of Au nanoparticles (NPs) is crucial for moderate bandgap semiconductors, because plasmonic resonance by interband excitations overlaps above the absorption edge of semiconductors, its critical role in water splitting is still not fully understood. Here, first, the plasmonic effects of shape‐controlled Au NPs on bismuth vanadate (BiVO₄) are studied, and a largely enhanced photoactivity of BiVO₄ is reported by introducing the octahedral Au NPs. The octahedral Au NP/BiVO₄ achieves 2.4 mA cm^?2 at the 1.23 V versus reversible hydrogen electrode, which is the threefold enhancement compared to BiVO₄. It is the highest value among the previously reported plasmonic Au NPs/BiVO₄. Improved photoactivity is attributed to the localized surface plasmon resonance; direct electron transfer (DET), plasmonic resonant energy transfer (PRET). The PRET can be stressed over DET when considering the moderate bandgap semiconductor. Enhanced water oxidation induced by the shape‐controlled Au NPs is applicable to moderate semiconductors, and shows a systematic study to explore new efficient plasmonic solar water splitting cells.     

Crafting Mussel‐Inspired Metal Nanoparticle‐Decorated Ultrathin Graphitic Carbon Nitride for the Degradation of Chemical Pollutants and Production of Chemical Resources

The development of efficient photocatalysts for the degradation of organic pollutants and production of hydrogen peroxide (H₂O₂) is an attractive two‐in‐one strategy to address environmental remediation concerns and chemical resource demands. Graphitic carbon nitride (g‐C₃N₄) possesses unique electronic and optical properties. However, bulk g‐C₃N₄ suffers from inefficient sunlight absorption and low carrier mobility. Once exfoliated, ultrathin nanosheets of g‐C₃N₄ attain much intriguing photocatalytic activity. Herein, a mussel‐inspired strategy is developed to yield silver‐decorated ultrathin g‐C₃N₄ nanosheets (Ag@U‐g‐C₃N₄‐NS). The optimum Ag@U‐g‐C₃N₄‐NS photocatalyst exhibits enhanced electrochemical properties and excellent performance for the degradation of organic pollutants. Due to the photoformed valence band holes and selective two‐electron reduction of O₂ by the conduction band electrons, it also renders an efficient, economic, and green route to light‐driven H₂O₂ production with an initial rate of 0.75 × 10^?6 m min^?1. The improved photocatalytic performance is primarily attributed to the large specific surface area of the U‐g‐C₃N₄‐NS layer, the surface plasmon resonance effect induced by Ag nanoparticles, and the cooperative electronic capture properties between Ag and U‐g‐C₃N₄‐NS. Consequently, this unique photocatalyst possesses the extended absorption region, which effectively suppresses the recombination of electron–hole pairs and facilitates the transfer of electrons to participate in photocatalytic reactions.     

Nanoparticle‐Enhanced Silver‐Nanowire Plasmonic Electrodes for High‐Performance Organic Optoelectronic Devices

Improved performance in plasmonic organic solar cells (OSCs) and organic light‐emitting diodes (OLEDs) via strong plasmon‐coupling effects generated by aligned silver nanowire (AgNW) transparent electrodes decorated with core–shell silver–silica nanoparticles (Ag@SiO₂NPs) is demonstrated. NP‐enhanced plasmonic AgNW (Ag@SiO₂NP–AgNW) electrodes enable substantially enhanced radiative emission and light absorption efficiency due to strong hybridized plasmon coupling between localized surface plasmons (LSPs) and propagating surface plasmon polaritons (SPPs) modes, which leads to improved device performance in organic optoelectronic devices (OODs). The discrete dipole approximation (DDA) calculation of the electric field verifies a strongly enhanced plasmon‐coupling effect caused by decorating core–shell Ag@SiO₂NPs onto the AgNWs. Notably, an electroluminescence efficiency of 25.33 cd A^?1 (at 3.2 V) and a power efficiency of 25.14 lm W^?1 (3.0 V) in OLEDs, as well as a power conversion efficiency (PCE) value of 9.19% in OSCs are achieved using hybrid Ag@SiO₂NP–AgNW films. These are the highest values reported to date for optoelectronic devices based on AgNW electrodes. This work provides a new design platform to fabricate high‐performance OODs, which can be further explored in various plasmonic and optoelectronic devices.     

Constructing Built‐in Electric Field in Ultrathin Graphitic Carbon Nitride Nanosheets by N and O Codoping for Enhanced Photocatalytic Hydrogen Evolution Activity

Codoping of N and O in ultrathin graphitic carbon nitride (g‐C₃N₄) nanosheets leads to an inner electric field. This field restrains the recombination of photogenerated carriers and, thus, enhances hydrogen evolution. The layered structure of codoped g‐C₃N₄ nanosheets (N‐O‐CNNS) not only provides abundant sites of contact with the reaction medium, but also decreases the distance over which the photogenerated electron–hole pairs are transported to the reaction interface. Quantum confinement in the ultrathin structure results in an increased bandgap and makes the photocatalytic reaction more favorable than bulk g‐C₃N₄. Under visible light irradiation, N‐O‐CNNS with 3 wt% Pt achieves a hydrogen evolution rate of 9.2 mmol g^?1 h^?1 and a value of 46.9 mmol g^?1 h^?1 under AM1.5 with 5 wt% Pt. Thus, this work paves the way for designing efficient nanostructures with increased separation/transfer efficiency of photogenerated carriers and, hence, increased photocatalytic activities.     

Hierarchical Porous O‐Doped g‐C3N4 with Enhanced Photocatalytic CO2 Reduction Activity

Artificial photosynthesis of hydrocarbon fuels by utilizing solar energy and CO₂ is considered as a potential route for solving ever‐increasing energy crisis and greenhouse effect. Herein, hierarchical porous O‐doped graphitic carbon nitride (g‐C₃N₄) nanotubes (OCN‐Tube) are prepared via successive thermal oxidation exfoliation and curling‐condensation of bulk g‐C₃N₄. The as‐prepared OCN‐Tube exhibits hierarchically porous structures, which consist of interconnected multiwalled nanotubes with uniform diameters of 20–30 nm. The hierarchical OCN‐Tube shows excellent photocatalytic CO₂ reduction performance under visible light, with methanol evolution rate of 0.88 µmol g^?1 h^?1, which is five times higher than bulk g‐C₃N₄ (0.17 µmol g^?1 h^?1). The enhanced photocatalytic activity of OCN‐Tube is ascribed to the hierarchical nanotube structure and O‐doping effect. The hierarchical nanotube structure endows OCN‐Tube with higher specific surface area, greater light utilization efficiency, and improved molecular diffusion kinetics, due to the more exposed active edges and multiple light reflection/scattering channels. The O‐doping optimizes the band structure of g‐C₃N₄, resulting in narrower bandgap, greater CO₂ affinity, and uptake capacity as well as higher separation efficiency of photogenerated charge carriers. This work provides a novel strategy to design hierarchical g‐C₃N₄ nanostructures, which can be used as promising photocatalyst for solar energy conversion.     

Multichannel Charge Transfer and Mechanistic Insight in Metal Decorated 2D–2D Bi2WO6–TiO2 Cascade with Enhanced Photocatalytic Performance

Promising semiconductor‐based photocatalysis toward achieving efficient solar‐to‐chemical energy conversion is an ideal strategy in response to the growing worldwide energy crisis, which however is often practically limited by the insufficient photoinduced charge‐carrier separation. Here, a rational cascade engineering of Au nanoparticles (NPs) decorated 2D/2D Bi₂WO₆–TiO₂ (B–T) binanosheets to foster the photocatalytic efficiency through the manipulated flow of multichannel‐enhanced charge‐carrier separation and transfer is reported. Mechanistic characterizations and control experiments, in combination with comparative studies over plasmonic Au/Ag NPs and nonplasmonic Pt NPs decorated 2D/2D B–T composites, together demonstrate the cooperative synergy effect of multiple charge‐carrier transfer channels in such binanosheets‐based ternary composites, including Z‐scheme charge transfer, “electron sink,” and surface plasmon resonance effect, which integratively leads to the boosted photocatalytic performance.     

Merging Single‐Atom‐Dispersed Iron and Graphitic Carbon Nitride to a Joint Electronic System for High‐Efficiency Photocatalytic Hydrogen Evolution

Scalable and sustainable solar hydrogen production via photocatalytic water splitting requires extremely active and stable light‐harvesting semiconductors to fulfill the stringent requirements of suitable energy band position and rapid interfacial charge transfer process. Motivated by this point, increasing attention has been given to the development of photocatalysts comprising intimately interfaced photoabsorbers and cocatalysts. Herein, a simple one‐step approach is reported to fabricate a high‐efficiency photocatalytic system, in which single‐site dispersed iron atoms are rationally integrated on the intrinsic structure of the porous crimped graphitic carbon nitride (g‐C₃N₄) polymer. A detailed analysis of the formation process shows that a stable complex is generated by spontaneously coordinating dicyandiamidine nitrate with iron ions in isopropanol, thus leading to a relatively complicated polycondensation reaction upon thermal treatment. The correlation of experimental and computational results confirms that optimized electronic structures of Fe@g‐C₃N₄ with an appropriate d‐band position and negatively shifting Fermi level can be achieved, which effectively gains the reducibility of electrons and creates more active sites for the photocatalytic reactions. As a result, the Fe@g‐C₃N₄ exhibits a highlighted intramolecular synergistic effect, performing greatly enhanced solar‐photon‐driven activities, including excellent photocatalytic hydrogen evolution rate (3390 µmol h^?1 g^?1, λ > 420 nm) and a reliable apparent quantum efficiency value of 6.89% at 420 nm.     

Faster Electron Injection and More Active Sites for Efficient Photocatalytic H2 Evolution in g‐C3N4/MoS2 Hybrid

Herein, the structural effect of MoS₂ as a cocatalyst of photocatalytic H₂ generation activity of g‐C₃N₄ under visible light irradiation is studied. By using single‐particle photoluminescence (PL) and femtosecond time‐resolved transient absorption spectroscopies, charge transfer kinetics between g‐C₃N₄ and two kinds of nanostructured MoS₂ (nanodot and monolayer) are systematically investigated. Single‐particle PL results show the emission of g‐C₃N₄ is quenched by MoS₂ nanodots more effectively than MoS₂ monolayers. Electron injection rate and efficiency of g‐C₃N₄/MoS₂‐nanodot hybrid are calculated to be 5.96 × 10⁹ s^?1 and 73.3%, respectively, from transient absorption spectral measurement, which are 4.8 times faster and 2.0 times higher than those of g‐C₃N₄/MoS₂‐monolayer hybrid. Stronger intimate junction between MoS₂ nanodots and g‐C₃N₄ is suggested to be responsible for faster and more efficient electron injection. In addition, more unsaturated terminal sulfur atoms can serve as the active site in MoS₂ nanodot compared with MoS₂ monolayer. Therefore, g‐C₃N₄/MoS₂ nanodot exhibits a 7.9 times higher photocatalytic activity for H₂ evolution (660 µmol g?¹ h^?1) than g‐C₃N₄/MoS₂ monolayer (83.8 µmol g^?1 h^?1). This work provides deep insight into charge transfer between g‐C₃N₄ and nanostructured MoS₂ cocatalysts, which can open a new avenue for more rationally designing MoS₂‐based catalysts for H₂ evolution.     

Synergy of Dopants and Defects in Graphitic Carbon Nitride with Exceptionally Modulated Band Structures for Efficient Photocatalytic Oxygen Evolution

Electronic structure greatly determines the band structures and the charge carrier transport properties of semiconducting photocatalysts and consequently their photocatalytic activities. Here, by simply calcining the mixture of graphitic carbon nitride (g‐C₃N₄) and sodium borohydride in an inert atmosphere, boron dopants and nitrogen defects are simultaneously introduced into g‐C₃N₄. The resultant boron‐doped and nitrogen‐deficient g‐C₃N₄ exhibits excellent activity for photocatalytic oxygen evolution, with highest oxygen evolution rate reaching 561.2 µmol h^?1 g^?1, much higher than previously reported g‐C₃N₄. It is well evidenced that with conduction and valence band positions substantially and continuously tuned by the simultaneous introduction of boron dopants and nitrogen defects into g‐C₃N₄, the band structures are exceptionally modulated for both effective optical absorption in visible light and much increased driving force for water oxidation. Moreover, the engineered electronic structure creates abundant unsaturated sites and induces strong interlayer C–N interaction, leading to efficient electron excitation and accelerated charge transport. In the present work, a facile approach is successfully demonstrated to engineer the electronic structures and the band structures of g‐C₃N₄ with simultaneous introduction of dopants and defects for high‐performance photocatalytic oxygen evolution, which can provide informative principles for the design of efficient photocatalysis systems for solar energy conversion.     

Formation of B?N?C Coordination to Stabilize the Exposed Active Nitrogen Atoms in g‐C3N4 for Dramatically Enhanced Photocatalytic Ammonia Synthesis Performance

It is an important issue that exposed active nitrogen atoms (e.g., edge or amino N atoms) in graphitic carbon nitride (g‐C₃N₄) could participate in ammonia (NH₃) synthesis during the photocatalytic nitrogen reduction reaction (NRR). Herein, the experimental results in this work demonstrate that the exposed active N atoms in g‐C₃N₄ nanosheets can indeed be hydrogenated and contribute to NH₃ synthesis during the visible‐light photocatalytic NRR. However, these exposed N atoms can be firmly stabilized through forming B? N? C coordination by means of B‐doping in g‐C₃N₄ nanosheets (BCN) with a B‐doping content of 13.8 wt%. Moreover, the formed B? N? C coordination in g‐C₃N₄ not only effectively enhances the visible‐light harvesting and suppresses the recombination of photogenerated carriers in g‐C₃N₄, but also acts as the catalytic active site for N₂ adsorption, activation, and hydrogenation. Consequently, the as‐synthesized BCN exhibits high visible‐light‐driven photocatalytic NRR activity, affording an NH₃ yield rate of 313.9 µmol g^?1 h^?1, nearly 10 times of that for pristine g‐C₃N₄. This work would be helpful for designing and developing high‐efficiency metal‐free NRR catalysts for visible‐light‐driven photocatalytic NH₃ synthesis.     

Quantitative Determination of Contribution by Enhanced Local Electric Field,Antenna‐Amplified Light Scattering,and Surface Energy Transfer to the Performance of Plasmonic Organic Solar Cells

Plasmonic metal nanostructures are widely used as subwavelength light concentrators to enhance light harvesting of organic solar cells through two photophysical effects, including enhanced local electric field (ELEF) and antenna‐amplified light scattering (AALS), while their adverse quenching effect from surface energy transfer (SET) should be suppressed. In this work, a comprehensive study to unambiguously distinguish and quantitatively determine the specific influence and contribution of each effect on the overall performance of organic solar cells incorporated with Ag@SiO₂ core–shell nanoparticles (NPs) is presented. By investigating the photon conversion efficiency (PCE) as a function of the SiO₂ shell thickness, a strong competition between the ELEF and SET effects in the performance of the devices with the NPs embedded in the active layers is found, leading to a maximum PCE enhancement of 12.4% at the shell thickness of 5 nm. The results give new insights into the fundamental understanding of the photophysical mechanisms responsible for the performance enhancement of plasmonic organic solar cells and provide important guidelines for designing more‐efficient plasmonic solar cells in general.     

From UV to Near‐Infrared Light‐Responsive Metal–Organic Framework Composites: Plasmon and Upconversion Enhanced Photocatalysis

The exploitation of photocatalysts that harvest solar spectrum as broad as possible remains a high‐priority target yet grand challenge. In this work, for the first time, metal–organic framework (MOF) composites are rationally fabricated to achieve broadband spectral response from UV to near‐infrared (NIR) region. In the core–shell structured upconversion nanoparticles (UCNPs)‐Pt@MOF/Au composites, the MOF is responsive to UV and a bit visible light, the plasmonic Au nanoparticles (NPs) accept visible light, whereas the UCNPs absorb NIR light to emit UV and visible light that are harvested by the MOF and Au once again. Moreover, the MOF not only facilitates the generation of “bare and clean” Au NPs on its surface and realizes the spatial separation for the Au and Pt NPs, but also provides necessary access for catalytic substrates/products to Pt active sites. As a result, the optimized composite exhibits excellent photocatalytic hydrogen production activity (280 µmol g^?1 h^?1) under simulated solar light, and the involved mechanism of photocatalytic H₂ production under UV, visible, and NIR irradiation is elucidated. Reportedly, this is an extremely rare study on photocatalytic H₂ production by light harvesting in all UV, visible, and NIR regions.     

Metal‐Free 2D/2D Phosphorene/g‐C3N4 Van der Waals Heterojunction for Highly Enhanced Visible‐Light Photocatalytic H2 Production

The generation of green hydrogen (H₂) energy using sunlight is of great significance to solve the worldwide energy and environmental issues. Particularly, photocatalytic H₂ production is a highly promising strategy for solar‐to‐H₂ conversion. Recently, various heterostructured photocatalysts with high efficiency and good stability have been fabricated. Among them, 2D/2D van der Waals (VDW) heterojunctions have received tremendous attention, since this architecture can promote the interfacial charge separation and transfer and provide massive reactive centers. On the other hand, currently, most photocatalysts are composed of metal elements with high cost, limited reserves, and hazardous environmental impact. Hence, the development of metal‐free photocatalysts is desirable. Here, a novel 2D/2D VDW heterostructure of metal‐free phosphorene/graphitic carbon nitride (g‐C₃N₄) is fabricated. The phosphorene/g‐C₃N₄ nanocomposite shows an enhanced visible‐light photocatalytic H₂ production activity of 571 µmol h^?1 g^?1 in 18 v% lactic acid aqueous solution. This improved performance arises from the intimate electronic coupling at the 2D/2D interface, corroborated by the advanced characterizations techniques, e.g., synchrotron‐based X‐ray absorption near‐edge structure, and theoretical calculations. This work not only reports a new metal‐free phosphorene/g‐C₃N₄ photocatalyst but also sheds lights on the design and fabrication of 2D/2D VDW heterojunction for applications in catalysis, electronics, and optoelectronics.     

Creating Graphitic Carbon Nitride Based Donor‐π–Acceptor‐π–Donor Structured Catalysts for Highly Photocatalytic Hydrogen Evolution

Conjugated polymers with tailored donor–acceptor units have recently attracted considerable attention in organic photovoltaic devices due to the controlled optical bandgap and retained favorable separation of charge carriers. Inspired by these advantages, an effective strategy is presented to solve the main obstructions of graphitic carbon nitride (g‐C₃N₄) photocatalyst for solar energy conversion, that is, inefficient visible light response and insufficient separation of photogenerated electrons and holes. Donor‐π–acceptor‐π–donor polymers are prepared by incorporating 4,4′‐(benzoc 1,2,5 thiadiazole‐4,7‐diyl) dianiline (BD) into the g‐C₃N₄ framework (UCN‐BD). Benefiting from the visible light band tail caused by the extended π conjugation, UCN‐BD possesses expanded visible light absorption range. More importantly, the BD monomer also acts as an electron acceptor, which endows UCN‐BD with a high degree of intramolecular charge transfer. With this unique molecular structure, the optimized UCN‐BD sample exhibits a superior performance for photocatalytic hydrogen evolution upon visible light illumination (3428 µmol h^?1 g^?1), which is nearly six times of that of the pristine g‐C₃N₄. In addition, the photocatalytic property remains stable for six cycles in 3 d. This work provides an insight into the synthesis of g‐C₃N₄‐based D‐π–A‐π–D systems with highly visible light response and long lifetime of intramolecular charge carriers for solar fuel production.     

The carboxylate magnetic – Zinc based metal-organic framework heterojunction: Fe3O4-COOH@ZIF-8/Ag/Ag3PO4 for plasmon enhanced visible light Z-scheme photocatalysis

In this work, magnetic nanoparticles (MNPs) grafted with carboxylic acid (Fe₃O₄-COOH MNPs) were successfully prepared from incorporation of glutaric anhydride as a functional group on the surface of the ferrite NPs. The MNP was used as a template to induce the growth of ZIF-8 metal–organic framework (MOF) on its surface. The Fe₃O₄-COOH@ZIF-8 core-shell was incorporated with silver phosphate (Ag₃PO₄) and Ag nanoparticles (Ag NPs) to develop a visible light active Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ photocatalyst. The materials were characterized using a range of techniques. The photocatalytic activity was investigated systematically by degrading an organo-phosphorus pesticide, diazinon under visible light irradiation. Among synthesized samples, the Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ heterostructured system exhibited highest photocatalytic activity and improved stability compared to others for the degradation of diazinon under visible light. The superior activity and improved stability of this heterostructured photocatalyst was attributed to the synergistic effects from surface plasmon resonance (SPR) of Ag NPs and sequential energy transfer via Z-scheme mechanism, for effective separation of electron-hole pairs. Radical-trapping experiments demonstrate that holes (h⁺) and O₂⁻ are primary reactive species involved in photocatalytic oxidation process. Moreover, the Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ photocatalyst did not show any obvious loss of photocatalytic activity during five cycle tests, which indicate that the heterostructured photocatalyst was highly stable and can be used repeatedly. Therefore, the work provides new insights into the design and fabrication of metal-organic frameworks (MOFs) for use as a visible light photocatalyst for degrading organic contaminants.     

Single Ni Atoms Anchored on Porous Few‐Layer g‐C3N4 for Photocatalytic CO2 Reduction: The Role of Edge Confinement

It is greatly intriguing yet remains challenging to construct single‐atomic photocatalysts with stable surface free energy, favorable for well‐defined atomic coordination and photocatalytic carrier mobility during the photoredox process. Herein, an unsaturated edge confinement strategy is defined by coordinating single‐atomic‐site Ni on the bottom‐up synthesized porous few‐layer g‐C₃N₄ (namely, Ni₅‐CN) via a self‐limiting method. This Ni₅‐CN system with a few isolated Ni clusters distributed on the edge of g‐C₃N₄ is beneficial to immobilize the nonedged single‐atomic‐site Ni species, thus achieving a high single‐atomic active site density. Remarkably, the Ni₅‐CN system exhibits comparably high photocatalytic activity for CO₂ reduction, giving the CO generation rate of 8.6 µmol g^?1 h^?1 under visible‐light illumination, which is 7.8 times that of pure porous few‐layer g‐C₃N₄ (namely, CN, 1.1 µmol g^?1 h^?1). X‐ray absorption spectrometric analysis unveils that the cationic coordination environment of single‐atomic‐site Ni center, which is formed by Ni‐N doping‐intercalation the first coordination shell, motivates the superiority in synergistic N–Ni–N connection and interfacial carrier transfer. The photocatalytic mechanistic prediction confirms that the introduced unsaturated Ni‐N coordination favorably binds with CO₂, and enhances the rate‐determining step of intermediates for CO generation.     

Highly efficient nanostructured metal-decorated hybrid semiconductors for solar conversion of CO2 with almost complete CO selectivity

Photocatalytic reduction of CO₂ into solar fuels is regarded as a promising method to address global warming and energy crisis problems. Although heterostructured hybrid metal oxide catalysts have been used for CO₂ reduction, selective control for CO production-only remains the subject of debate. In this paper, we report an absolute selectivity for CO production-only with enhanced photocatalytic ability using Ag-decorated reduced titanium oxide/tungsten hybrid nanoparticles (blue TiO₂/WO₃–Ag HNPs) at 1166.72 μmol g⁻¹ h⁻¹ with an apparent quantum yield of 34.8%. The construction of a Z-scheme between blue TiO₂ and WO₃ domains with an excellent band alignment provided remarkably improved separation of photoinduced charges. Importantly, the presence of novel Ag not only produces the highest selectivity up to 100% CO production-only, but also increases the photocatalytic electron reaction rate (2333.44 μmol g⁻¹ h⁻¹).     

A Hierarchical Z‑Scheme α‐Fe2O3/g‐C3N4 Hybrid for Enhanced Photocatalytic CO2 Reduction

The challenge in the artificial photosynthesis of fossil resources from CO₂ by utilizing solar energy is to achieve stable photocatalysts with effective CO₂ adsorption capacity and high charge‐separation efficiency. A hierarchical direct Z‐scheme system consisting of urchin‐like hematite and carbon nitride provides an enhanced photocatalytic activity of reduction of CO₂ to CO, yielding a CO evolution rate of 27.2 µmol g^?1 h^?1 without cocatalyst and sacrifice reagent, which is >2.2 times higher than that produced by g‐C₃N₄ alone (10.3 µmol g^?1 h^?1). The enhanced photocatalytic activity of the Z‐scheme hybrid material can be ascribed to its unique characteristics to accelerate the reduction process, including: (i) 3D hierarchical structure of urchin‐like hematite and preferable basic sites which promotes the CO₂ adsorption, and (ii) the unique Z‐scheme feature efficiently promotes the separation of the electron–hole pairs and enhances the reducibility of electrons in the conduction band of the g‐C₃N₄. The origin of such an obvious advantage of the hierarchical Z‐scheme is not only explained based on the experimental data but also investigated by modeling CO₂ adsorption and CO adsorption on the three different atomic‐scale surfaces via density functional theory calculation. The study creates new opportunities for hierarchical hematite and other metal‐oxide‐based Z‐scheme system for solar fuel generation.     

Surface Engineering for Extremely Enhanced Charge Separation and Photocatalytic Hydrogen Evolution on g‐C3N4

Reinforcing the carrier separation is the key issue to maximize the photocatalytic hydrogen evolution (PHE) efficiency of graphitic carbon nitride (g‐C₃N₄). By a surface engineering of gradual doping of graphited carbon rings within g‐C₃N₄, suitable energy band structures and built‐in electric fields are established. Photoinduced electrons and holes are impelled into diverse directions, leading to a 21‐fold improvement in the PHE rate.     

Black Phosphorus Revisited: A Missing Metal‐Free Elemental Photocatalyst for Visible Light Hydrogen Evolution

Metal‐free elemental photocatalysts for hydrogen (H₂) evolution are more advantageous than the traditional metal‐based inorganic photocatalysts since the nonmetal elements are generally cheaper, more earth‐abundant, and environmentally friendly. Black phosphorus (BP) has been attracting increasing attention in recent years based on its anisotropic 2D layered structure with tunable bandgap in the range of 0.3–2.0 eV; however, the application of BP for photocatalytic H₂ evolution has been scarcely reported experimentally although being theoretically predicted. Herein, for the first time, the visible light photocatalytic H₂ evolution of BP nanosheets prepared via a facile solid‐state mechanochemical method by ball‐milling bulk BP is reported. Without using any noble metal cocatalyst, the visible light photocatalytic hydrogen evolution rate of BP nanosheets reaches 512 µmol h^?1 g^?1, which is ≈18 times higher than that of the bulk BP, and is comparable or even higher than that of graphitic carbon nitrides (g‐C₃N₄).