Pt–Cu Interaction Induced Construction of Single Pt Sites for Synchronous Electron Capture and Transfer in Photocatalysis

Single-atom photocatalysts have shown their fascinating strengths in enhancing charge transfer dynamics; however, rationally designing coordination sites by metal doping to stabilize isolated atoms is still challenging. Here, a one-unit-cell ZnIn₂S₄ (ZIS) nanosheet with abundant Cu dopants serving as the suitable support to achieve a single atom Pt catalyst (Pt₁/Cu–ZIS) is reported, and hence the metal single atom–metal dopant interaction at an atomic level is disclosed. Experimental results and density functional theory calculations highlight the unique stabilizing effect (Pt–Cu interaction) of single Pt atoms in Cu-doped ZIS, while apparent Pt clusters are observed in pristine ZIS. Specifically, Pt–Cu interaction provides an extra coordination site except three S sites on the surface, which induces a higher diffusion barrier and makes the single atom more stable on the surface. Apart from stabilizing Pt single atoms, Pt–Cu interaction also serves as the efficient channel to transfer electrons from Cu trap states to Pt active sites, thereby enhancing the charge separation and transfer efficiency. Remarkably, the Pt₁/Cu–ZIS exhibits a superb activity, giving a photocatalytic hydrogen evolution rate of 5.02 mmol g⁻¹ h⁻¹, nearly 49 times higher than that of pristine ZIS.     

Double-Tuned RuCo Dual Metal Single Atoms and Nanoalloy with Synchronously Expedited Volmer/Tafel Kinetics for Effective and Ultrastable Ampere-Level Current Density Hydrogen Production

Alkaline water electrolysis system is of general interest but is impeded by the unsatisfactory hydrogen evolution reaction (HER) performance under ampere-level current density. Herein, the synchronous modification of complicated Volmer/Tafel kinetics is effectuated for attaining ampere-level current density hydrogen production via engineering double-tuned RuCo nanoalloy and dual metal single atoms on hierarchical N-doped mesoporous carbon (RuCo@Ru_SACo_SA-NMC). The electronic structure of Ru sites in dual metal single atoms can be synergistically tailored by adjacent Co atomic sites and nanoalloy, which makes it achieve faster Volmer kinetics with rapid water adsorption/dissociation and transfer rates toward adsorbed hydroxyl. While double-tuned Ru sites in nanoalloy by adjacent alloyed Co sites and dual metal single atoms undertake optimized Tafel kinetics with boosted transfer rates toward adsorbed hydrogen. Accordingly, RuCo@Ru_SACo_SA-NMC exhibits ultralow HER overpotential of 255 mV at 1 A cm⁻² with robust stability over 24 days, ultrahigh mass activity of 37.2 A mg_Ru⁻¹, and turnover frequency of 19.5 s⁻¹. More importantly, RuCo@Ru_SACo_SA-NMC can make water electrolysis system possess low power consumption of 5.34 kWh per Nm³_H2 and estimated costs of 1.197 $ per kg_H2. The concept emphasized in this study provides guidance for rational design of cost-effective catalysts with ampere-level current density hydrogen production.     

Symbiotically Reinforced Bimetallic Photocatalysis in Conjugated Metal−Organic Framework Nanosheets

Compared to monometallic counterparts, bimetallic two-dimensional conjugated metal-organic framework (2D c-MOF) nanosheets possess preferable metal tunability and synergistic effect for performance optimization, yet rarely developed in photocatalytic hydrogen evolution to date. In this study, a feasible post-synthetic strategy of second metal installation (SMI) is proposed and applied to construct a crystalline bimetallic 2D c-MOF nanosheet, HTHATN-Ni-Pt-NS. HTHATN-Ni-Pt-NS exhibits high electrical conductivity and efficient hydrogen evolution with the rate of 47.2 mmol g⁻¹ h⁻¹, which is 13.5-fold higher than that of pristine HTHATN-Ni-NS without Pt^II decoration under visible light irradiation. Experimental and theoretical analysis reveal that introduction of low amount of Pt^II provides catalytically active metal sites and optimizes the ΔG_H* value of Ni^II centers, thus resulting in the enhanced performance of proton reduction. This study represents the first example of symbiotic bimetallic centers in MOF nanosheets highlighting SMI strategy as an efficient approach to construct photocatalysts.     

Preparation and characterization of the brownmillerite Sr2Co2O5 as novel photocatalyst in the hydrogen generation

Sr₂Co₂O₅ is a semiconductor belonging to the brownmillerite family; it is prepared by nitrate route and the photo-electrochemical properties are assessed for the first time for the photocatalytic hydrogen production. Thermal analysis indicates the formation of the semiconductor phase at 750 °C. An optical transition at 1.10 eV, directly allowed is obtained from the diffuse reflectance spectrum, due to the internal Co³⁺: d-d transition in octahedral coordination. A flat band potential of 0.037 V_SCE is determined in KOH solution (0.1 M) from the Mott-Schottky characteristic and the results are relevant for the water reduction. The conduction band of Sr₂Co₂O₅ (−0.85 V_SCE), deriving from Co³⁺: 3d orbital is more cathodic than the potential of H₂O/H₂ couple and hydrogen is successfully evolved under visible light. A rate evolution of 68 µmol (g catalyst)⁻¹ min⁻¹ at pH ∼ 12 and a light-to-chemical energy efficiency of 0.82% are determined.     

Atomistic Structural Engineering of Conjugated Microporous Polymers Promotes Photocatalytic Biomass Valorization

Polymer photocatalysts have great promise for solar fuel production due to their flexible structural and functional designability. However, their photocatalytic efficiencies are still unsatisfactory, limited by their intrinsically large exciton binding energy and fast charge recombination. Herein, the atomistic structural engineering of donor–acceptor (D−A) polymer photocatalysts for enhanced charge separation and photocatalytic hydrogen production is proposed. By changing the electron affinity of the acceptor units, the electron delocalization and exciton binding energy of the polymeric networks can be readily tuned, resulting in enhanced charge separation efficiency and photocatalytic activity. The optimal sample shows the highest H₂ production rate of 3207 µmol g⁻¹ h⁻¹ in the presence of ascorbic acid as the sacrificial agent. Moreover, the photocatalytic H₂ production can be coupled with almost stoichiometrical conversion of 5-hydroxymethyl furfural to 2,5-diformylfuran.     

Enhanced Photocatalytic Hydrogen Evolution from Organic Ternary Heterojunction Nanoparticles Featuring a Compact Alloy-Like Phase

Organic semiconductor nanoparticles (NPs) are attractive photocatalysts to produce hydrogen from water splitting. Herein, a ternary strategy of incorporating crystalline n-type molecule IDMIC-4F into the host system made of p-type polymer PM6 and n-type molecule ITCC-M is demonstrated. ITCC-M and IDMIC-4F form compact alloy-like composite with shorter lattice spacing in the ternary p/n heterojunction NPs, resulting in enhanced exciton dissociation and charge transfer characteristics. As the result, an unprecedented hydrogen evolution rate (HER) of 307 mmol h⁻¹ g⁻¹ and a maximum apparent quantum efficiency of 5.9% at 600 nm are achieved in the optimized ternary NPs (PM6:ITCC-M:IDMIC-4F = 1:1.3:0.2), which is among the highest HER from organic photocatalysts to the best of the authors’ knowledge. The alloy-like composite also improves the operational stability of ternary NP photocatalysts. This study shows that synergizing two compatible n-type small molecules to form alloy-like composite is a promising approach to design novel organic photocatalysts for boosting the photocatalytic hydrogen evolution efficiency.     

Atomic-Level Surface Engineering of Nickel Phosphide Nanoarrays for Efficient Electrocatalytic Water Splitting at Large Current Density

Designing high-performance and cost-effective electrocatalysts for water splitting at high current density is pivotal for practical industrial applications. Herein, it is found that atomic-level surface engineering of self-supported nickel phosphide (NiP) nanoarrays via a facile cation-exchange method can substantially regulate the chemical and physical properties of catalysts by introducing Co atoms. Such surface-engineered Ni_xCo_1–xP endows several aspects of merits: i) rough nanosheet array electrode structure accessible to diffusion of electrolytes and release of gas bubbles, ii) enriched P vacancies companied by Co doping and thus increased active sites, and iii) the synergy of Ni₅P₄ and NiP₂ beneficial to catalytic activity enhancement. By virtue of finely controlling the Co contents, the optimal Ni_0.96Co_0.04P electrode achieves remarkable bifunctional electrocatalytic performance for overall water splitting at a large current density of 1000 mA cm⁻², showing overpotentials of 249.7 mV for hydrogen evolution reaction and 281.7 mV for oxygen evolution reaction. Furthermore, the Ni_0.96Co_0.04P electrode at 500 mA cm⁻² exhibits an ultralow potential (1.71 V) and ultralong durability (500 h) for overall water splitting. This study implies that the atomic-level surface engineering of the electrode materials offers a viable route for gaining high-performance catalysts for water splitting at large current density.     

Simultaneously Tuning Band Structure and Oxygen Reduction Pathway toward High-Efficient Photocatalytic Hydrogen Peroxide Production Using Cyano-Rich Graphitic Carbon Nitride

The demands for green production of hydrogen peroxide have triggered extensive studies in the photocatalytic synthesis, but most photocatalysts suffer from rapid charge recombination and poor 2e⁻ oxygen reduction reaction (ORR) selectivity. Here, a novel composite photocatalyst of cyano-rich graphitic carbon nitride g-C₃N₄ is fabricated in a facile manner by sodium chloride-assisted calcination on dicyandiamide. The obtained photocatalysts exhibit superior activity (7.01 mm  h⁻¹ under λ  ≥  420 nm, 16.05 mm  h⁻¹ under simulated sun conditions) for H₂O₂ production and 93% selectivity for 2e⁻ ORR, much higher than that of the state-of-the-art photocatalyst. The porous g-C₃N₄ with Na dopants and cyano groups simultaneously optimize two limiting steps of the photocatalytic 2e⁻ ORR: photoactivity, and selectivity. The cyano groups can adjust the band structure of g-C₃N₄ to achieve high activity. They also serve as oxygen adsorption sites, in which local charge polarization facilitates O₂ adsorption and protonation. With the aid of Na⁺, the O₂ is reduced to produce more superoxide radicals as the intermediate products for H₂O₂ synthesis. This work provides a facile approach to simultaneously tune photocatalytic activity and 2e⁻ ORR selectivity for boosting H₂O₂ production, and then paves the way for the practical application of g-C₃N₄ in environmental remediation and energy supply.     

Anisotropic Ag2S–Au Triangular Nanoprisms with Desired Configuration for Plasmonic Photocatalytic Hydrogen Generation in Visible/Near‐Infrared Region

Anisotropic Ag₂S‐edged Au‐triangular nanoprisms (TNPs) are constructed by controlling preferential overgrowth of Ag₂S as plasmonic photocatalysts for hydrogen generation. Under visible and near‐infrared light irradiation, Ag₂S‐edged Au‐TNPs exhibit almost fourfold higher efficiency (796 µmol h⁻¹ g⁻¹) than those of Ag₂S‐covered Au‐TNPs (216 µmol h⁻¹ g⁻¹) and pure Au‐TNPs in hydrogen generation. A single‐particle photoluminescence study demonstrates that the plasmon‐induced hot electrons transfer from Au‐TNPs to Ag₂S for hydrogen generation. Finite‐difference‐time‐domain simulations verify that the corners/edges of Au‐TNPs are high‐curvature sites with maximum electric field distributions facilitating hot electron generation and transfer. Therefore, Ag₂S‐edged Au‐TNPs are efficient plasmonic photocatalyst with the desired configurations for charge separation boosting hydrogen generation.     

Hierarchically Porous Carbonized Wood Decorated with MoNi4-Embedded MoO2 Nanosheets: An Efficient Electrocatalyst for Water Splitting

Development of low-cost electrocatalysts for water splitting is crucial to economical hydrogen production. Here, a highly efficient electrocatalyst composed of MoNi₄-embedded amorphous MoO₂ nanosheets grown on less-tortuosity hierarchically porous carbonized wood (MoNi₄/MoO₂@CW) is reported. The generation of abundant MoNi₄/MoO₂ heterointerfaces and defects-rich MoO₂ significantly promote the adsorption and activation of reactant molecules on the MoNi₄/MoO₂@CW. The obtained MoNi₄/MoO₂@CW catalyst exhibits ultralow overpotentials of 22 and 205 mV for hydrogen evolution reaction and oxygen evolution reaction at a current density of 10 mA cm⁻², respectively. The catalyst can be used for dual-function electrodes and assembling two-electrode electrolyzer illustrates 10 mA cm⁻² at 1.47 V and superior durability over 24 h for overall water electrolysis. Moreover, it also possesses a high mass activity of 142 Ag⁻¹ MoNi₄ at 200 mV, surpassing the Pt/C catalyst (132 Ag⁻¹). The outstanding performance of the MoNi₄/MoO₂@CW is attributed to the decrease in energy barrier for water dissociation, optimal adsorption/desorption of H/O-intermediates, and fast mass transport through the porous structure, as confirmed by experimental results and density functional theory-based calculations. The MoNi₄/MoO₂@CW electrocatalyst has excellent potential for practical water splitting.     

Heteroatom- and Bonded Z-Scheme Channels-Modulated Ultrafast Carrier Dynamics and Exciton Dissociation in Covalent Triazine Frameworks for Efficient Photocatalytic Hydrogen Evolution

Covalent triazine frameworks (CTF) offer a tunable platform for photocatalytic H₂ generation due to their diverse structures, low costs, and precisely tunable electronic structures. However, high exciton binding energy and short lifetimes of photogenerated carriers restrict their application in photocatalytic hydrogen evolution. Herein, a novel phosphorus-incorporated CTF is introduced to construct a chemically bonded PCTF/WO₃ (PCTFW) heterostructure with a precise interface electron transfer channel. The phosphorus incorporation is found to dominantly reduce the exciton binding energy and promote the dissociation of singlet and triplet excitons into free charge carriers due to the regulation of electronic structures. High-quality interfacial W N bonds improve the interfacial transfer of photogenerated electrons, thus prolonging the lifetime of photogenerated electrons. Femtosecond transient absorption spectroscopy characterizations and DFT calculations further confirm both phosphorus incorporation and Z-scheme heterojunctions can synergistically boost the in-built electric field and accelerate the migration and separation of photogenerated electrons. The optimized photocatalytic H₂-evolution rate of resultant PCTFW is 134.84 µmol h⁻¹ (67.42 mmol h⁻¹g⁻¹), with an apparent quantum efficiency of 37.63% at 420 nm, surpassing many reported CTF-based photocatalysts so far. This work highlights the significance of atom-level interfacial exciton dissociation, and charge transfer and separation in improving photocatalysis.     

Planar-Coordination PdSe2 Nanosheets as Highly Active Electrocatalyst for Hydrogen Evolution Reaction

The coordination environment is crucial for the activity of an electrocatalyst, which defines the interaction between the central and adjacent atoms. In traditional 2D MX₂ (M = Mo, W, etc., X = S, Se), M is usually coordinated with 6 X atoms in either trigonal prismatic (2H) or octahedral (1T) polyhedrons. With such a coordination configuration, only the edge X sites exhibit activity for hydrogen evolution reaction (HER). Here, a planar-coordination transition metal chalcogenide, PdSe₂ is reported, as an efficient electrocatalyst for the HER in an alkaline electrolyte. By reducing the spatial polyhedron coordination to planar polygon coordination, the M sites in PdSe₂ can be efficiently activated to interact with the adsorptive intermediates. As a result, both Pd and Se atoms act as active sites for hydrogen evolution with neutral adsorption ability. With an overpotential of 138 mV at 10 mA cm⁻², this work advances the exploration of planar-coordination HER electrocatalysts.     

Biphasic Transition Metal Nitride Electrode Promotes Nucleophile Oxidation Reaction for Practicable Hybrid Water Electrocatalysis

Glycerol electrooxidation (GOR), as a typical nucleophile oxidation reaction, is deemed as a promising alternative anodic route to assist cathodic hydrogen evolution reaction. However, the investigations of high-performance catalysts and industrial-scale application of GOR remain a grand challenge. Herein, biphasic Ni₃N/Co₃N heterostructure nanowires (denoted as Ni₃N/Co₃N-NWs) are proposed as an efficient bifunctional catalyst, which realizes a high Faradaic efficiency of 94.6% toward formate production. Importantly, the flow electrolyzer achieves an industry-level current density of 1 A cm⁻² at 2.01 V with impressive stability for steady running over 200 h, realizing lower electricity expense of 4.82 kWh m⁻³_H2 and energy saving efficiency of 9.7%, as well as outstanding co-production rates of 11 and 21.4 mmol cm⁻² h⁻¹ toward formate and H₂, respectively. Theoretical calculations reveal that the efficient electron transfer on Ni₃N/Co₃N heterointerfaces simultaneously optimizes nucleophile reaction tendency and glycerol dehydrogenation kinetics, thus contributing to excellent GOR performance.     

Nanoscaling and Heterojunction for Photocatalytic Hydrogen Evolution by Bimetallic Metal-Organic Frameworks

Using sunlight to manufacture hydrogen offers promising access to renewable clean energy. For this, low-cost photocatalyst with effective light absorption and charge transfer are crucial, as current top-performing systems often involve precious metals like Pd and Pt. An integrated organic–inorganic photocatalyst based on the cheap metals of iron and nickel are reported, wherein the metal ions form strong metal-sulfur bonds with the organic linker molecules (2,5-dimercapto-1,4-benzenedicarboxylic acid, H₄DMBD) to generate 2D coordination sheets for promoting light absorption and charge transport. The 2D sheets are further modified through ionic metal-carboxylate moieties to allow for functional flexibility. Thus, high-surface-area thin nanosheets of this 2D material, with an optimized Fe/Ni ratio (0.25:1.75), and in heterojunction with CdS nanosheet, achieve a stable photocatalytic hydrogen evolution rate of 12.15 µmol mg⁻¹ h⁻¹. This work synergizes coordination network design and nano-assembly as a versatile platform for catalyzing hydrogen production and other sustainable processes.     

Engineering Active Iron Sites on Nanoporous Bimetal Phosphide/Nitride Heterostructure Array Enabling Robust Overall Water Splitting

Alkaline water electrolysis is a commercially viable technology for green H₂ production using renewable electricity from intermittent solar or wind energy, but very few non-noble bifunctional catalysts simultaneously exhibit superb catalytic efficiency and stability at large current densities for hydrogen and oxygen evolution reactions (HER and OER, respectively), especially for iron-based catalysts. Given that iron is the most abundant and least expensive transition metal, iron-based compounds are very attractive low-cost targets as active electrocatalysts for bifunctional water splitting with large-current durability. Herein, the in situ construction of a self-supported Fe₂P/Co₂N porous heterostructure arrays possessing superb bifunctional catalytic activity in base is reported, featured by low overpotentials of 131 and 283 mV to attain a current density of 500 mA cm⁻² for HER and OER, respectively, outperforming most of non-noble bifunctional electrocatalysts reported hitherto. Particularly, this hybrid catalyst also displays an excellent overall water splitting activity, requiring low voltages of 1.561 and 1.663 V to attain 100 and 500 mA cm⁻² with excellent durability in 1 m KOH, respectively. Most importantly, the catalyst is stable for >120 h, even when the current density is 500 mA cm⁻², which is prominently superior to IrO₂⁽⁺⁾//Pt⁽⁻⁾ coupled noble electrodes, and is among the very best bifunctional catalysts reported thus far. Detailed theoretical calculations reveal that the interfacial interaction between Fe₂P and Co₂N can further improve the H* binding energy at the iron sites.     

Highly efficient visible-light driven AgBr/Ag3PO4 hybrid photocatalysts with enhanced photocatalytic activity

Highly efficient visible-light-driven AgBr/Ag₃PO₄ hybrid photocatalysts with different mole ratios of AgBr were prepared via an in-situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgBr/Ag₃PO₄ photocatalysts displayed the higher photocatalytic activity than pure Ag₃PO₄ and AgBr for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgBr/Ag₃PO₄ with 60% of AgBr exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgBr/Ag₃PO₄ readily transformed to be Ag@AgBr/Ag₃PO₄ system while the photocatalytic activity of AgBr/Ag₃PO₄ remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h⁺ and O₂^∙− play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgBr/Ag₃PO₄ hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag₃PO₄, Ag and AgBr, in which Ag nanoparticles act as the charge separation center.     

Mo-/Co-N-C Hybrid Nanosheets Oriented on Hierarchical Nanoporous Cu as Versatile Electrocatalysts for Efficient Water Splitting

Designing robust and cost-effective electrocatalysts based on Earth-abundant elements is crucial for large-scale hydrogen production through electrochemical water splitting. Here, nitrogen-doped carbon engrafted Mo₂N/CoN hybrid nanosheets that are seamlessly oriented on hierarchical nanoporous Cu scaffold (Mo-/Co-N-C/Cu), as highly efficient electrocatalysts for alkaline hydrogen evolution reaction are reported. The constituent heterostructured Mo₂N/CoN nanosheets work as bifunctional electroactive sites for both water dissociation and adsorption/desorption of hydrogen intermediates while the nitrogen-doped carbon bridges electron transfers between electroactive sites and interconnective Cu current collectors by making use of Mo-/Co-N-C bonds and intimate C/Cu contacts at interfaces. As a consequence of unique architecture having electroactive sites to be sufficiently accessible, self-supported nanoporous Mo-/Co-N-C/Cu hybrid electrodes exhibit outstanding electrocatalysis in 1 m KOH, with a negligible onset overpotential and a low Tafel slope of 47 mV dec⁻¹. They only take overpotential of as low as 230 mV to reach current density of 1000 mA cm⁻². When coupled with their electro-oxidized derivatives that mediate efficiently the oxygen evolution reaction, the alkaline water electrolyzer can achieve ≈100 mA cm⁻² at 1.622 V in 1 m KOH electrolyte, ≈0.343 V lower than the device constructed with commercially available Pt/C and Ir/C nanocatalysts immobilized on nanoporous Cu electrodes.     

Cocatalyst Engineering with Robust Tunable Carbon-Encapsulated Mo-Rich Mo/Mo2C Heterostructure Nanoparticle for Efficient Photocatalytic Hydrogen Evolution

Cocatalyst engineering with non-noble metal nanomaterials can play a vital role in low-cost, sustainable, and large-scale photocatalytic hydrogen production. This research adopts slow carburization and simultaneous hydrocarbon reduction to synthesize carbon-encapsulated Mo/Mo₂C heterostructure nanoparticles, namely Mo/Mo₂C@C cocatalyst. Experimental and theoretical investigations indicate that the Mo/Mo₂C@C cocatalysts have a nearly ideal hydrogen-adsorption free energy (ΔG_H*), which results in the accelerated HER kinetics. As such, the cocatalysts are immobilized onto organic polymer semiconductor g-C₃N₄ and inorganic semiconductor CdS, resulting in Mo/Mo₂C@C/g-C₃N₄ and Mo/Mo₂C@C/CdS catalysts, respectively. In photocatalytic hydrogen evolution application under visible light, the Mo/Mo₂C@C with g-C₃N₄ and CdS can form the Schottky junctions via appropriate band alignment, greatly suppressing the recombination of photoinduced electron-hole pairs. The surface carbon layer as the conducting scaffolds and Mo metal facilitates electron transfer and electron-hole separation, favoring structural stability and offering more reaction sites and interfaces as electron mediators. As a result, these catalysts exhibit high H₂ production rates of 2.7 mmol h⁻¹ g⁻¹ in basic solution and 98.2 mmol h⁻¹ g⁻¹ in acidic solution, respectively, which is significantly higher than that of the bench-mark Pt-containing catalyst. The proposed cocatalyst engineering approach is promising in developing efficient non-noble metal cocatalysts for rapid hydrogen production.     

A Low-Cost,Durable Bifunctional Electrocatalyst Containing Atomic Co and Pt Species for Flow Alkali-Al/Acid Hybrid Fuel Cell and Zn–Air Battery

Transition metal single atoms anchored on nitrogen-doped carbon (M-N-C) matrix with M-N-C active sites have shown to be promising catalysts for both hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). Herein, a hybrid catalyst with low-level loading of atomic Pt and Co species encapsulated in nitrogen-doped graphene (Pt@CoN₄-G) is developed. The Pt@CoN₄-G shows low overpotential for HER in wide-pH electrolyte and manifests improved mass activity with almost eight times greater than that of Pt/C at an overpotential of 50 mV. The Pt@CoN₄-G also exhibits a top-level ORR activity (half-wave potential, E_1/2 = 0.893 V) and robust stability (>200 h) in alkaline medium. Using theoretical calculations and comprehensive characterizations , the strong metal–support interactions between Pt species and CoN₄-G support and synergistical cooperation of multiple active sites are clarified. A flow alkali-Al/acid hybrid fuel cell using Pt@CoN₄-G as cathode catalyst delivers a large power density of 222 mW cm⁻² with excellent stability to achieve simultaneously hydrogen evolution and electricity generation. In addition, Pt@CoN₄-G endows a flow Zn-air battery with high power density (316 mW cm⁻²), good stability under large current density (>100 h at 100 mA cm⁻²), and long cycle life (over 600 h at 5 mA cm⁻²).     

Generalized Synthetic Strategy for Amorphous Transition Metal Oxides-Based 2D Heterojunctions with Superb Photocatalytic Hydrogen and Oxygen Evolution

2D amorphous transition metal oxides (a-TMOs) heterojunctions that have the synergistic effects of interface (efficiently promoting the separation of electron−hole pairs) and amorphous nature (abundant defects and dangling bonds) have attracted substantial interest as compelling photocatalysts for solar energy conversion. Strategies to facilely construct a-TMOs-based 2D/2D heterojunctions is still a big challenge due to the difficulty of preparing individual amorphous counterparts. A generalized synthesis strategy based on supramolecular self-assembly for bottom–up growth of a-TMOs-based 2D heterojunctions is reported, by taking 2D/2D g-C₃N₄ (CN)/a-TMOs heterojunction as a proof-of-concept. This strategy primarily depends on controlling the cooperation of the growth of supramolecular precursor and the coordinated covalent bonds arising from the tendency of metal ions to attain the stable configuration of electrons, which is independent on the intrinsic character of individual metal ion, indicating it is universally applicable. As a demonstration, the structure, physical properties, and photocatalytic water-splitting performance of CN/a-ZnO heterojunction are systematically studied. The optimized 2D/2D CN/a-ZnO exhibits enhanced photocatalytic performance, the hydrogen (432.6 µmol h⁻¹ g⁻¹) and oxygen (532.4 µmol h⁻¹ g⁻¹) evolution rate are 15.5 and 12.2 times than bulk CN, respectively. This synthetic strategy is useful to construct 2D a-TMOs nanomaterials for applications in energy-related areas and beyond.