Flexible and Binder‐Free Electrodes of Sb/rGO and Na3V2(PO4)3/rGO Nanocomposites for Sodium‐Ion Batteries

Flexible power sources have shown great promise in next‐generation bendable, implantable, and wearable electronic systems. Here, flexible and binder‐free electrodes of Na₃V₂(PO₄)₃/reduced graphene oxide (NVP/rGO) and Sb/rGO nanocomposites for sodium‐ion batteries are reported. The Sb/rGO and NVP/rGO paper electrodes with high flexibility and tailorability can be easily fabricated. Sb and NVP nanoparticles are embedded homogenously in the interconnected framework of rGO nanosheets, which provides structurally stable hosts for Na‐ion intercalation and deintercalation. The NVP/rGO paper‐like cathode delivers a reversible capacity of 113 mAh g^?1 at 100 mA g^?1 and high capacity retention of ≈96.6% after 120 cycles. The Sb/rGO paper‐like anode gives a highly reversible capacity of 612 mAh g^?1 at 100 mA g^?1, an excellent rate capacity up to 30 C, and a good cycle performance. Moreover, the sodium‐ion full cell of NVP/rGO//Sb/rGO has been fabricated, delivering a highly reversible capacity of ≈400 mAh g^?1 at a current density of 100 mA g^?1 after 100 charge/discharge cycles. This work may provide promising electrode candidates for developing next‐generation energy‐storage devices with high capacity and long cycle life.     

Enhanced Photocatalytic H2‐Production Activity of CdS Quantum Dots Using Sn2+ as Cocatalyst under Visible Light Irradiation

Herein, oil‐soluble CdS quantum dots (QDs) are first prepared through a solvent‐thermal process. Then, oil‐soluble CdS QDs are changed into water‐soluble QDs via ligand exchange using mercaptopropionic acid as capping agent at pH 13. The photocatalytic performance is investigated under the visible light irradiation using glycerol as sacrificial agent and Sn²⁺ as cocatalyst. No H₂‐production activity is observed for oil‐soluble CdS QDs. Water‐soluble CdS QDs exhibit significantly enhanced hydrogen evolution rate. When the concentration of cocatalyst Sn²⁺ increases to 0.2 × 10^?3 m , the rate of hydrogen evolution reaches 1.61 mmol g^?1 h^?1, which is 24 times higher than that of the pristine water‐soluble CdS QDs. The enhanced H₂‐production efficiency is attributed to the adsorption of Sn²⁺ ions on the surface of CdS QDs that are further reduced to Sn atoms by photogenerated electrons. The in situ generated Sn atoms serve as photocatalytic cocatalyst for efficient hydrogen generation.     

Golden Bristlegrass‐Like Hierarchical Graphene Nanofibers Entangled with N‐Doped CNTs Containing CoSe2 Nanocrystals at Each Node as Anodes for High‐Rate Sodium‐Ion Batteries

Golden bristlegrass‐like unique nanostructures comprising reduced graphene oxide (rGO) matrixed nanofibers entangled with bamboo‐like N‐doped carbon nanotubes (CNTs) containing CoSe₂ nanocrystals at each node (denoted as N‐CNT/rGO/CoSe₂ NF) are designed as anodes for high‐rate sodium‐ion batteries (SIBs). Bamboo‐like N‐doped CNTs (N‐CNTs) are successfully generated on the rGO matrixed nanofiber surface, between rGO sheets and mesopores, and interconnected chemically with homogeneously distributed rGO sheets. The defects in the N‐CNTs formed by a simple etching process allow the complete phase conversion of Co into CoSe₂ through the efficient penetration of H₂Se gas inside the CNT walls. The N‐CNTs bridge the vertical defects for electron transfer in the rGO sheet layers and increase the distance between the rGO sheets during cycles. The discharge capacity of N‐CNT/rGO/CoSe₂ NF after the 10 000th cycle at an extremely high current density of 10 A g^?1 is 264 mA h g^?1, and the capacity retention measured at the 100th cycle is 89%. N‐CNT/rGO/CoSe₂ NF has final discharge capacities of 395, 363, 328, 304, 283, 263, 246, 223, 197, 171, and 151 mA h g^?1 at current densities of 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 A g^?1, respectively.     

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).     

A Single‐Step Hydrothermal Route to 3D Hierarchical Cu2O/CuO/rGO Nanosheets as High‐Performance Anode of Lithium‐Ion Batteries

As anodes of Li‐ion batteries, copper oxides (CuO) have a high theoretical specific capacity (674 mA h g^?1) but own poor cyclic stability owing to the large volume expansion and low conductivity in charges/discharges. Incorporating reduced graphene oxide (rGO) into CuO anodes with conventional methods fails to build robust interaction between rGO and CuO to efficiently improve the overall anode performance. Here, Cu₂O/CuO/reduced graphene oxides (Cu₂O/CuO/rGO) with a 3D hierarchical nanostructure are synthesized with a facile, single‐step hydrothermal method. The Cu₂O/CuO/rGO anode exhibits remarkable cyclic and high‐rate performances, and particularly the anode with 25 wt% rGO owns the best performance among all samples, delivering a record capacity of 550 mA h g^?1 at 0.5 C after 100 cycles. The pronounced performances are attributed to the highly efficient charge transfer in CuO nanosheets encapsulated in rGO network and the mitigated volume expansion of the anode owing to its robust 3D hierarchical nanostructure.     

Large‐Scale Synthesis of Freestanding Layer‐Structured PbI2 and MAPbI3 Nanosheets for High‐Performance Photodetection

Recently, due to the possibility of thinning down to the atomic thickness to achieve exotic properties, layered materials have attracted extensive research attention. In particular, PbI₂, a kind of layered material, and its perovskite derivatives, CH₃NH₃PbI₃ (i.e., MAPbI₃), have demonstrated impressive photoresponsivities for efficient photodetection. Herein, the synthesis of large‐scale, high‐density, and freestanding PbI₂ nanosheets is demonstrated by manipulating the microenvironment during physical vapor deposition. In contrast to conventional two‐dimensional (2D) growth along the substrate surface, the essence here is the effective nucleation of microplanes with different angles relative to the in‐plane direction of underlying rough‐surfaced substrates. When configured into photodetectors, the fabricated device exhibits a photoresponsivity of 410 mA W^?1, a detectivity of 3.1 × 10¹¹ Jones, and a fast response with the rise and decay time constants of 86 and 150 ms, respectively, under a wavelength of 405 nm. These PbI₂ nanosheets can also be completely converted into MAPbI₃ materials via chemical vapor deposition with an improved photoresponsivity up to 40 A W^?1. All these performance parameters are comparable to those of state‐of‐the‐art layered‐material‐based photodetectors, revealing the technological potency of these freestanding nanosheets for next‐generation high‐performance optoelectronics.     

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.     

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.     

CuCo2S4–rGO Microflowers: First‐Principle Calculation and Application in Energy Storage

This paper demonstrates the ability of a CuCo₂S₄–reduced graphene oxide (rGO) composite to perform robust electrochemical performances applying to supercapacitors (SCs) and lithium ion batteries (LIBs). The first‐principle calculation based on density functional theory is conducted to study the electronic property of CuCo₂O₄ and CuCo₂S₄ and provide a theoretical basis for this work. Then, the 3D spinel‐structured CuCo₂O₄ and CuCo₂S₄ microflowers are synthesized and compared as electrodes for both SCs and LIBs. The CuCo₂S₄ microflowers can provide a larger specific surface area, which enlarges the contact area between the electrode material and the electrolyte and contributes to high‐efficiency electrochemical reactions. The reduced graphene oxides are coated on the CuCo₂S₄ microflowers, therefore effectively increasing the conductivity, and further absorbing the stress produced in the reaction process. As an electrode of a symmetric supercapacitor, the optimized CuCo₂S₄–rGO composite exhibits an energy density of 16.07 Wh kg^?1 and a maximum power density of 3600 W kg^?1. Moreover, the CuCo₂S₄–rGO composite can also be used as an anode for lithium ion batteries, exhibiting a reversible capacity of 1050 mAh g^?1 after 140 cycles at the current density of 200 mA g^?1. The galvanostatic intermittence titration techniques also reveal superior Li‐ion diffusion behavior of the CuCo₂S₄–rGO composite during redox reactions.     

Multidimensional Synergistic Nanoarchitecture Exhibiting Highly Stable and Ultrafast Sodium‐Ion Storage

Conversion‐type anodes with multielectron reactions are beneficial for achieving a high capacity in sodium‐ion batteries. Enhancing the electron/ion conductivity and structural stability are two key challenges in the development of high‐performance sodium storage. Herein, a novel multidimensionally assembled nanoarchitecture is presented, which consists of V₂O₃ nanoparticles embedded in amorphous carbon nanotubes that are then coassembled within a reduced graphene oxide (rGO) network, this materials is denoted V₂O₃?C‐NTs?rGO. The selective insertion and multiphase conversion mechanism of V₂O₃ in sodium‐ion storage is systematically demonstrated for the first time. Importantly, the naturally integrated advantages of each subunit synergistically provide a robust structure and rapid electron/ion transport, as confirmed by in situ and ex situ transmission electron microscopy experiments and kinetic analysis. Benefiting from the synergistic effects, the V₂O₃?C‐NTs?rGO anode delivers an ultralong cycle life (72.3% at 5 A g^?1 after 15 000 cycles) and an ultrahigh rate capability (165 mAh g^?1 at 20 A g^?1, ≈30 s per charge/discharge). The synergistic design of the multidimensionally assembled nanoarchitecture produces superior advantages in energy storage.     

A Biopolymer Heparin Sodium Interlayer Anchoring TiO2 and MAPbI3 Enhances Trap Passivation and Device Stability in Perovskite Solar Cells

Traps in the photoactive layer or interface can critically influence photovoltaic device characteristics and stabilities. Here, traps passivation and retardation on device degradation for methylammonium lead trihalide (MAPbI₃) perovskite solar cells enabled by a biopolymer heparin sodium (HS) interfacial layer is investigated. The incorporated HS boosts the power conversion efficiency from 17.2 to 20.1% with suppressed hysteresis and Shockley–Read–Hall recombination, which originates primarily from the passivation of traps near the interface between the perovskites and the TiO₂ cathode. The incorporation of an HS interfacial layer also leads to a considerable retardation of device degradation, by which 85% of the initial performance is maintained after 70 d storage in ambient environment. Aided by density functional theory calculations, it is found that the passivation of MAPbI₃ and TiO₂ surfaces by HS occurs through the interactions of the functional groups (? COO^?, ? SO₃^?, or Na⁺) in HS with undersaturated Pb and I ions in MAPbI₃ and Ti⁴⁺ in TiO₂. This work demonstrates a highly viable and facile interface strategy using biomaterials to afford high‐performance and stable perovskite solar cells.     

Photostriction of CH3NH3PbBr3 Perovskite Crystals

Organic–inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light–matter interactions. The photoinduced strain of CH₃NH₃PbBr₃ is investigated using high‐resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH₃NH₃PbBr₃ is calculated as 2.08 × 10^?8 m² W^?1 at room temperature under visible light illumination. The significant photostriction of CH₃NH₃PbBr₃ is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation–rotation coupling. Unlike CH₃NH₃PbI₃, it is noted that the photostriction of CH₃NH₃PbBr₃ is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH₃NH₃PbBr₃ for applications in next‐generation optical micro‐electromechanical devices.     

Nitrogen‐Doped Graphene‐Buffered Mn2O3 Nanocomposite Anodes for Fast Charging and High Discharge Capacity Lithium‐Ion Batteries

Mn₂O₃ is a promising anode material for lithium‐ion batteries (LIBs) because of its high theoretical capacity and low discharge potential. However, low electronic conductivity and capacity fading limits its practical application. In this work, Mn₂O₃ with 1D nanowire geometry is synthesized in neutral aqueous solutions by a facile and effective hydrothermal strategy for the first time, and then Mn₂O₃ nanoparticle and nitrogen‐doped reduced graphene oxide (N‐rGO) are composited with Mn₂O₃ nanowires (Mn₂O₃‐GNCs) to enhance its volume utilization and conductivity. When used as an anode material for LIBs, the Mn₂O₃‐GNCs exhibit high reversible capacity (1350 mAh g^?1), stable cycling stability, and good rate capability. Surprisingly, the Mn₂O₃‐GNC electrodes can also show fast charging capability; even after 200 cycles (charge: 10 A g^?1; discharge: 0.5 A g^?1), its discharge capacity can also keep at ≈500 mAh g^?1. In addition, the Mn₂O₃‐GNCs also have considerable full cell and supercapacitor performance. The excellent electrochemical performances can be ascribed to the N‐rGO network structure and 1D nanowire structure, which can ensure fast ion and electron transportation.     

A Multifunctional Tb‐MOF for Highly Discriminative Sensing of Eu3+/Dy3+ and as a Catalyst Support of Ag Nanoparticles

Exploring novel multifunctional rare earth materials is very important because these materials have fundamental interests, such as new structural facts and connecting modes, as well as potential technological applications, including optics, magnetic properties, sorption, and catalytic behaviors. Especially, employing these nanomaterials for sensing or catalytic reactions is still very challenging. Herein, a new superstable, anionic terbium‐metal–organic‐framework, [H₂N(CH₃)₂][Tb(cppa)₂(H₂O)₂], (China Three Gorges University ( CTGU‐1 ), H₂cppa = 5‐(4‐carboxyphenyl)picolinic acid), is successfully prepared, which can be used as a turn‐on, highly‐sensitive fluorescent sensor to detect Eu³⁺ and Dy³⁺, with a detection limitation of 5 × 10^?8 and 1 × 10^?4m in dimethylformamide, respectively. This result represents the first example of lanthanide‐metal–organic‐frameworks (Ln‐MOF) that can be employed as a discriminative fluorescent probe to recognize Eu³⁺ and Dy³⁺. In addition, through ion exchanging at room temperature, Ag(I) can be readily reduced in situ and embedded in the anionic framework, which leads to the formation of nanometal‐particle@Ln‐MOF composite with uniform size and distribution. The as‐prepared Ag@ CTGU‐1 shows remarkable catalytic performance to reduce 4‐nitrophenol, with a reduction rate constant κ as large as 2.57 × 10^?2 s^?1; almost the highest value among all reported noble‐metal‐nanoparticle@MOF composites.     

Anchoring and Upgrading Ultrafine NiPd on Room‐Temperature‐Synthesized Bifunctional NH2‐N‐rGO toward Low‐Cost and Highly Efficient Catalysts for Selective Formic Acid Dehydrogenation

Hydrogen is widely considered to be a sustainable and clean energy alternative to the use of fossil fuels in the future. Its high hydrogen content, nontoxicity, and liquid state at room temperature make formic acid a promising hydrogen carrier. Designing highly efficient and low‐cost heterogeneous catalysts is a major challenge for realizing the practical application of formic acid in the fuel‐cell‐based hydrogen economy. Herein, a simple but effective and rapid strategy is proposed, which demonstrates the synthesis of NiPd bimetallic ultrafine particles (UPs) supported on NH₂‐functionalized and N‐doped reduced graphene oxide (NH₂‐N‐rGO) at room temperature. The introduction of the ? NH₂? N group to rGO is the key reason for the formation of the ultrafine and well‐dispersed Ni_0.4Pd_0.6 UPs (1.8 nm) with relatively large surface area and more active sites. Surprisingly, the as‐prepared low‐cost NiPd/NH₂‐N‐rGO dsiplays excellent hydrophilicity, 100% H₂ selectivity, 100% conversion, and remarkable catalytic activity (up to 954.3 mol H₂ (mol catalyst)^?1 h^?1) for FA decomposition at room temperature even with no additive, which is much higher than that of the best catalysts so far reported.     

Cross‐Linked g‐C3N4/rGO Nanocomposites with Tunable Band Structure and Enhanced Visible Light Photocatalytic Activity

Cross‐linked rather than non‐covalently bonded graphitic carbon nitride (g‐C₃N₄)/reduced graphene oxide (rGO) nanocomposites with tunable band structures have been successfully fabricated by thermal treatment of a mixture of cyanamide and graphene oxide with different weight ratios. The experimental results indicate that compared to pure g‐C₃N₄, the fabricated CN/rGO nanocomposites show narrowed bandgaps with an increased in the rGO ratio. Furthermore, the band structure of the CN/rGO nanocomposites can be readily tuned by simply controlling the weight ratio of the rGO. It is found that an appropriate rGO ratio in nanocomposite leads to a noticeable positively shifted valence band edge potential, meaning an increased oxidation power. The tunable band structure of the CN/rGO nanocomposites can be ascribed to the formation of C?O?C covalent bonding between the rGO and g‐C₃N₄ layers, which is experimentally confirmed by Fourier transform infrared (FT‐IR) and X‐ray photoelectron (XPS) data. The resulting nanocomposites are evaluated as photocatalysts by photocatalytic degradation of rhodamine B (RhB) and 4‐nitrophenol under visible light irradiation (λ > 400 nm). The results demonstrate that the photocatalytic activities of the CN/rGO nanocomposites are strongly influenced by rGO ratio. With a rGO ratio of 2.5%, the CN/rGO‐2.5% nanocomposite exhibits the highest photocatalytic efficiency, which is almost 3.0 and 2.7 times that of pure g‐C₃N₄ toward photocatalytic degradation of RhB and 4‐nitrophenol, respectively. This improved photocatalytic activity could be attributed to the improved visible light utilization, oxidation power, and electron transport property, due to the significantly narrowed bandgap, positively shifted valence band‐edge potential, and enhanced electronic conductivity.     

3D Nitrogen‐Anion‐Decorated Nickel Sulfides for Highly Efficient Overall Water Splitting

Developing non‐noble‐metal electrocatalysts with high activity and low cost for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is of paramount importance for improving the generation of H₂ fuel by electrocatalytic water‐splitting. This study puts forward a new N‐anion‐decorated Ni₃S₂ material synthesized by a simple one‐step calcination route, acting as a superior bifunctional electrocatalyst for the OER/HER for the first time. The introduction of N anions significantly modifies the morphology and electronic structure of Ni₃S₂, bringing high surface active sites exposure, enhanced electrical conductivity, optimal HER Gibbs free‐energy (ΔG_H*), and water adsorption energy change (ΔG_H2O*). Remarkably, the obtained N‐Ni₃S₂/NF 3D electrode exhibits extremely low overpotentials of 330 and 110 mV to reach a current density of 100 and 10 mA cm^?2 for the OER and HER in 1.0 m KOH, respectively. Moreover, an overall water‐splitting device comprising this electrode delivers a current density of 10 mA cm^?2 at a very low cell voltage of 1.48 V. Our finding introduces a new way to design advanced bifunctional catalysts for water splitting.     

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.     

Highly Efficient 2D/3D Hybrid Perovskite Solar Cells via Low‐Pressure Vapor‐Assisted Solution Process

The fabrication of multidimensional organometallic halide perovskite via a low‐pressure vapor‐assisted solution process is demonstrated for the first time. Phenyl ethyl‐ammonium iodide (PEAI)‐doped lead iodide (PbI₂) is first spin‐coated onto the substrate and subsequently reacts with methyl‐ammonium iodide (MAI) vapor in a low‐pressure heating oven. The doping ratio of PEAI in MAI‐vapor‐treated perovskite has significant impact on the crystalline structure, surface morphology, grain size, UV–vis absorption and photoluminescence spectra, and the resultant device performance. Multiple photoluminescence spectra are observed in the perovskite film starting with high PEAI/PbI₂ ratio, which suggests the coexistence of low‐dimensional perovskite (PEA₂MA_n?1Pb_nI_3n+1) with various values of n after vapor reaction. The dimensionality of the as‐fabricated perovskite film reveals an evolution from 2D, hybrid 2D/3D to 3D structure when the doping level of PEAI/PbI₂ ratio varies from 2 to 0. Scanning electron microscopy images and Kelvin probe force microscopy mapping show that the PEAI‐containing perovskite grain is presumably formed around the MAPbI₃ perovskite grain to benefit MAPbI₃ grain growth. The device employing perovskite with PEAI/PbI₂ = 0.05 achieves a champion power conversion efficiency of 19.10% with an open‐circuit voltage of 1.08 V, a current density of 21.91 mA cm^?2, and a remarkable fill factor of 80.36%.     

Mesoporous Polymeric Cyanamide‐Triazole‐Heptazine Photocatalysts for Highly‐Efficient Water Splitting

Conjugated polymers are promising light harvesters for water reduction/oxidation due to their simple synthesis and adjustable bandgap. Herein, both cyanamide and triazole functional groups are first incorporated into a heptazine‐based carbon nitride (CN) polymer, resulting in a mesoporous conjugated cyanamide‐triazole‐heptazine polymer (CTHP) with different compositions by increasing the quantity of cyanamide/triazole units in the CN backbone. Varying the compositions of CTHP modulates its electronic structures, mesoporous morphologies, and redox energies, resulting in a significantly improved photocatalytic performance for both H₂ and O₂ evolution under visible light irradiation. A remarkable H₂ evolution rate of 12723 µmol h^?1 g^?1 is observed, resulting in a high apparent quantum yield of 11.97% at 400 nm. In parallel, the optimized photocatalyst also exhibits an O₂ evolution rate of 221 µmol h^?1 g^?1, 9.6 times higher than the CN counterpart, with the value being the highest among the reported CN‐based bifunctional photocatalysts. This work provides an efficient molecular engineering approach for the rational design of functional polymeric photocatalysts.