Intermediate Energies Research Articles

Unraveling the crucial contribution of additive chromate to efficient and stable alkaline seawater oxidation on Ni-based layered double hydroxides

Seawater electrolysis to generate hydrogen offers a clean, green, and sustainable solution for new energy. However, the catalytic activity and durability of anodic catalysts are plagued by the corrosion and competitive oxidation reactions of chloride in high concentrations. In this study, we find that the additive CrO42− anions in the electrolyte can not only promote the formation and stabilization of the metal oxyhydroxide active phase but also greatly mitigate the adverse effect of Cl− on the anode. Linear sweep voltammetry, accelerated corrosion experiments, corrosion polarization curves, and charge transfer resistance results indicate that the addition of CrO42− distinctly improves oxygen evolution reaction (OER) kinetics and corrosion resistance in alkaline seawater electrolytes. Especially, the introduction of CrO42− even in the highly concentrated NaCl (2.5 M) electrolyte prolongs the durability of NiFe-LDH to almost five times the case without CrO42−. Density functional theory calculations also reveal that the adsorption of CrO42− can tune the electronic configuration of active sites of metal oxyhydroxides, enhance conductivity, and optimize the intermediate adsorption energies. This anionic additive strategy can give a better enlightenment for the development of efficient and stable oxygen evolution reactions for seawater electrolysis.

Theoretical design of bifunctional single-atom catalyst over g-C2N2 for oxygen evolution and reduction reactions

The two-dimensional graphitic carbon nitride (g-CxNy) is a promising support for electrochemistry catalysts owing to its stability and controllable chemical composition. Here, by density functional theory (DFT) a serial of transition metal single-atom catalysts (SAC) supported on the g-C2N2 with vacancy (denoted as TM1/C2N2, TM=Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir and Pt) were studied for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The non-noble Ni and Co single atom exhibited relatively strong binding energies over the defective g-C2N2 support. The d-band center of TM performed a good descriptor for adsorption free energies of intermediates. For OER, the overpotential of non-noble Co1/C2N2 was as low as 0.30 V, comparable to Rh1/C2N2. For ORR, both Co1/C2N2 and Rh1/C2N2 displayed excellent performance with overpotentials of around 0.50 V. The volcano plot revealed that the proper binding strength of O* and OH* on Co1/C2N2 rendered it an excellent bifunctional catalyst for both OER and ORR. Considering the superior performance of Co SAC over g-C2N2 than not only g-C3N4 but also defective graphene, we postulate that there could exist an optimized C/N ratio of carbon-rich g-CxNy support for improving the non-noble Co SAC activity on oxygen electrode.

Balancing electron transfer and intermediate adsorption ability of metallic Ni-Fe-RE-P bifunctional catalysts via 4f-2p-3d electron interaction for enhanced water splitting

Balancing electron transfer and intermediate adsorption ability of bifunctional catalysts via tailoring electronic structures is crucial for green hydrogen production, while it still remains challenging due to lacking efficient strategies. Herein, one efficient and universal strategy is developed to greatly regulate electronic structures of the metallic Ni-Fe-P catalysts via in-situ introducing the rare earth (RE) atoms (Ni-Fe-RE-P, RE = La, Ce, Pr, and Nd). Accordingly, the as-prepared optimal Ni-Fe-Ce-P/CC self-supported bifunctional electrodes exhibited superior electrocatalytic activity and excellent stability with the low overpotentials of 247 and 331 mV at 100 mA cm−2 for HER and OER, respectively. In the assembled electrolyzer, the Ni-Fe-Ce-P/CC as bifunctional electrodes displayed low operation potential of 1.49 V to achieve a current density of 10 mA cm−2, and the catalytic performance can be maintained for 100 h. Experimental results combined with density functional theory (DFT) calculation reveal that Ce doping leads to electron decentralization and crystal structure distortion, which can tailor the band structures and d-band center of Ni-Fe-P, further increasing conductivity and optimizing intermediate adsorption energy. Our work not only proposes a valuable strategy to regulate the electron transfer and intermediate adsorption of electrocatalysts via RE atoms doping, but also provides a deep understanding of regulation mechanism of metallic electrocatalysts for enhanced water splitting.

Activity trends of Pd clusters supported on C2N for oxygen evolution and reduction reactions

Developing highly efficient electrocatalysts for the oxygen evolution reaction (OER) and reduction reaction (ORR) is crucial for future renewable energy technology. Here, we use first-principles calculations combined with genetic algorithm to determine the structures of various Pd clusters supported on experimentally available C2N monolayer and evaluate the OER and ORR performance. Our findings show that the activity of the supported Pd clusters is closely linked to the local geometrical and electronic structure of the active site. Furthermore, we establish the activity trends of the clusters based on the adsorption free energies of intermediates. In particular, C2N supported Pd7 and Pd8 clusters exhibit outstanding OER activity with low overpotentials. We identify a volcano relation for the OER on the clusters, suggesting that the high activity of the cluster is related to the moderate adsorption strength of intermediates. Mechanistic analysis indicates that the second water formation is the potential-determining step for ORR on the clusters due to the strong adsorption of *OH. Additionally, we identify a linear scaling relationship between the ORR overpotentials and adsorption free energies of *OH, demonstrating that reducing the adsorption strength of reaction intermediates on Pd clusters can improve the activity. This work unravels the activity trends of cluster catalysts and provides strategies for the rational design of highly efficient single-cluster catalysts for OER and ORR.

Bimetallic iron complex constructed clusters and single atoms neighboring structure to enhance oxygen reduction reaction performance

Electrocatalysts are useful in lowering the energy barrier in oxygen reduction reaction (ORR). In this study, a catalyst with neighboring Fe single-atom and cluster is created by adsorbing a bimetallic Fe complex onto N-doped carbon and then pyrolyzing it. The resulting catalyst has good performance and a half-wave potential of 0.89 V. When used in Zn-air batteries, the voltage drops by only 8.13 % after 145 h of cycling. Theoretical studies show that electrons transfer from neighboring clusters to single atoms and the catalyst has a lower d-band center. These reduce intermediate desorption energy, hence improving ORR performance. This work demonstrates the capacity to adjust the catalytic properties through the interaction of diverse metal structures, which helps to design more efficient catalysts.

Heterostructural NiFeW disulfide and hydroxide dual‐trimetallic core‐shell nanosheets for synergistically effective water oxidation

AbstractA stable and highly active core‐shell heterostructure electrocatalyst is essential for catalyzing oxygen evolution reaction (OER). Here, a dual‐trimetallic core‐shell heterostructure OER electrocatalyst that consists of a NiFeWS2 inner core and an amorphous NiFeW(OH)z outer shell is designed and synthesized using in situ electrochemical tuning. The electrochemical measurements of different as‐synthesized catalysts with a similar mass loading suggest that the core‐shell Ni0.66Fe0.17W0.17S2@amorphous NiFeW(OH)z nanosheets exhibit the highest overall performance compared with that of other bimetallic reference catalysts for the OER. Additionally, the nanosheet arrays were in situ grown on hydrophilic‐treated carbon paper to fabricate an integrated three‐dimensional electrode that affords a current density of 10 mA cm−2 at a small overpotential of 182 mV and a low Tafel slope of 35 mV decade−1 in basic media. The Faradaic efficiency of core‐shell Ni0.66Fe0.17W0.17S2@amorphous NiFeW(OH)z is as high as 99.5% for OER. The scanning electron microscope, transmission electron microscope, and X‐ray photoelectron spectroscopy analyses confirm that this electrode has excellent stability in morphology and elementary composition after long‐term electrochemical measurements. Importantly, density functional theory calculations further indicate that the core‐shell heterojunction increased the conductivity of the catalyst, optimized the adsorption energy of the OER intermediates, and improved the OER activity. This study provides a universal strategy for designing more active core‐shell structure electrocatalysts based on the rule of coordinated regulation between electronic transport and active sites.

Unraveling the deactivation mechanism of Co-LiH composite catalyst for ammonia synthesis at milder conditions

An efficient ammonia synthesis catalyst that operates under mild conditions has been a long-cherished goal in heterogeneous catalysis. The challenges associated with low-temperature ammonia synthesis arise from both the activation of inert N2 molecules and the presence of scaling relations between reactant dissociation and intermediate adsorption energies. Transition metals-metal hydride (TM-MH) composite catalysts have shown promise to overcome these challenges as both TM and MH actively participate in the reaction, enabling improved ammonia synthesis rates at lower temperatures (150 ºC). Considering this prospect, two types of Co-LiH catalyst were synthesized by ball-milling of precursors (CoCl2 and LiH- denoted as Co-LiH(rxn)) and pure components (Co and LiH- denoted as Co-LiH(pur)), and their catalytic activity was evaluated at several reaction conditions to investigate the stability for long-term operation. Co-LiH(rxn) was found to deactivate in less than 150 h whereas Co-LiH(pur) displayed a continuous production although the synthesis rate was 3 times lower than the former. Structural characterization techniques, such as XRD, SEM, and TEM were used, and it was found that Co metal in the FCC phase was primarily sintered due to its small particle size in the fresh catalyst. Temperature-programmed desorption (TPD) test on the spent Co-LiH(rxn) catalyst also displayed an ammonia release profile similar to that of LiNH2 decomposition, which confirms the presence of ammonia in the spent catalyst structure. Hence, another major finding is speculated that irreversible ammonia absorption by LiH at the target ammonia reaction conditions contributes to the deactivation of the catalyst and the formation of intermediate compounds that are required for continuous ammonia generation in this composite catalyst.

Isospin Correlations in Isotope Yields at Intermediate and High Energy Heavy-Ion Collisions

Isospin Correlations in Isotope Yields at Intermediate and High Energy Heavy-Ion Collisions

Optimization optical and radiation shielding properties via controlling the Hirshfeld topological constraints: A case study of carbonate-based crystals

This work explores the potential of carbonate-based ceramics (CBC) as materials for optical and radiation shielding applications. The results reveal the distinctive behavior of various CBC materials in shielding γ-rays. At an intermediate energy of E = 0.5 MeV, SiO2 has a MAC value of 0.087, whereas the MAC values for the CBCs are as follows: (CMs, MAC (g/cm2)): (CaCO3, 0.088), (MgCO3, 0.087), (SrCO3, 0.086), (BaCO3, 0.096), (ZnCO3, 0.086), (CdCO3, 0.091), and (PbCO3, 0.145). Also, the effective atomic numbers (Zeff) found to range from 11.03 to 78.82. These values surpass those of silicon dioxide (SiO2), highlighting the superior γ-ray attenuation capabilities of CBC. The work also delves also into the optical properties of CBC materials, highlighting the interplay between density (2.61 < ρ < 6.72 g/cm3), band gap energy (2.680<Eg < 5.050 eV), and refractive index (1.99254 < n < 2.48905). Furthermore, the study delves into the impact of charge density within Hirshfeld voids on these properties, revealing that as the interatomic interactions increase: 2.1% < O⋯C<26.8%, 9.3% < O⋯O<26.3%, or 63.3% < O … A2⁺<86.4% (A = Ca, Mg, Sr, Ba, Zn, Cd) due to higher charge density, thus the LAC and n values may tune among the studied CBC. The fine-tuning of topological and charge density distributions within the crystal's voids offers a promising avenue to optimize these materials for enhanced radiation shielding effectiveness or optical properties. This interplay between crystal structure, composition, charge distribution, Hirshfeld topological constraints as key factors in determining their radiation attenuation and optical capabilities was explored.

Heterojunction of MXenes and MN4–graphene: Machine learning to accelerate the design of bifunctional oxygen electrocatalysts

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential for the development of excellent bifunctional electrocatalysts, which are key functions in clean energy production. The emphasis of this study lies in the rapid design and investigation of 153 MN4–graphene (Gra)/ MXene (M2NO) electrocatalysts for ORR/OER catalytic activity using machine learning (ML) and density functional theory (DFT). The DFT results indicated that CoN4–Gra/Ti2NO had both good ORR (0.37 V) and OER (0.30 V) overpotentials, while TiN4–Gra/M2NO and MN4–Gra/Cr2NO had high overpotentials. Our research further indicated orbital spin polarization and d-band centers far from the Fermi energy level, affecting the adsorption energy of oxygen-containing intermediates and thus reducing the catalytic activity. The ML results showed that the gradient boosting regression (GBR) model successfully predicted the overpotentials of the monofunctional catalysts RhN4–Gra/Ti2NO (ORR, 0.39 V) and RuN4–Gra/W2NO (OER, 0.45 V) as well as the overpotentials of the bifunctional catalyst RuN4–Gra/W2NO (ORR, 0.39 V; OER, 0.45 V). The symbolic regression (SR) algorithm was used to construct the overpotential descriptors without environmental variable features to accelerate the catalyst screening and shorten the trial-and-error costs from the source, providing a reliable theoretical basis for the experimental synthesis of MXene heterostructures.

Modulating metal-carrier interaction of high-loading Co-Al2O3-SiO2 catalysts for boosted N-propylcarbazole hydrogenation

We developed a series of high-loading Co-Al2O3-SiO2 catalysts to enhance the hydrogenation of N-propylcarbazole (NPCZ) by fine-tuning the Al/Si ratio. Our research reveals that adjusting this ratio can significantly modify the electronic structure of Co nanoparticles, as confirmed by XPS, H2-TPD, and CO-DRIFT analyses, thereby affecting the adsorption of hydrogen species and their interaction with unsaturated π-bonds of NPCZ intermediates. Optimal Al concentration promotes Co nanoparticles dispersion, while excessive Al leads to increased acidity and reduced surface area. The Co70/Al4Si1O catalyst, with an Al/Si ratio of 4, demonstrated superior hydrogenation efficiency by enabling fast and stable hydrogenation of NPCZ, achieving an activation energy of 64.53 kJ/mol and maintaining high performance over 10 cycles. Through DFT calculations, we explored the d-band center and Bader charge across 6 different Co10/Al-Si-O models and assessed the adsorption energies of NPCZ intermediates, along with the energetics of three stepwise reactions. The initial hydrogenation step from NPCZ to 4H-NPCZ is predominantly influenced by the catalyst's acidity/basicity, whereas the subsequent deeper hydrogenation steps of 4H-NPCZ and 8H-NPCZ are governed by the d-π feedback interaction between the metal and the adsorbate. This research offers critical guidance on selecting optimal supports for Co-based catalysts in LOHC hydrogenation.

Dynamic Reconstruction of Two-Dimensional Defective Bi Nanosheets for Efficient Electrocatalytic Urea Synthesis.

Catalyst surface dynamics drive the generation of active species for electrocatalytic reactions. Yet, the understanding of dominant site formation and reaction mechanisms is limited. In this study, we thoroughly investigate the dynamic reconstruction of two-dimensional defective Bi nanosheets from exfoliated Bi2Se3 nanosheets under electrochemical CO2 and nitrate (NO3 -) reduction conditions. The ultrathin Bi2Se3 nanosheets obtained by NaBH4-assisted cryo-mediated liquid-phase exfoliation are more easily reduced and reconstructed to Bi nanosheets with high-density grain boundaries (GBs; GB-rich Bi). The reconstructed GB-rich Bi catalyst affords a remarkable yield rate of 4.6 mmol h-1 mgcat. -1 and Faradaic efficiency of 32 % for urea production at -0.40 V vs. RHE. Notably, this yield rate is 2 and 8.2 times higher than those of the low-GB Bi and bulk Bi catalysts, respectively. Theoretical analysis demonstrates that the GB sites significantly reduce the *CO and *NH2 intermediate formation energy and C-N coupling energy barrier, enabling selective urea electrosynthesis on the GB-rich Bi catalyst. This work will trigger further research into the structure-activity interplay in dynamic processes using in situ techniques.

Dynamic Reconstruction of Two‐Dimensional Defective Bi Nanosheets for Efficient Electrocatalytic Urea Synthesis

AbstractAbstract:Catalyst surface dynamics drive the generation of active species for electrocatalytic reactions. Yet, the understanding of dominant site formation and reaction mechanisms is limited. In this study, we thoroughly investigate the dynamic reconstruction of two‐dimensional defective Bi nanosheets from exfoliated Bi2Se3 nanosheets under electrochemical CO2 and nitrate (NO3−) reduction conditions. The ultrathin Bi2Se3 nanosheets obtained by NaBH4‐assisted cryo‐mediated liquid‐phase exfoliation are more easily reduced and reconstructed to Bi nanosheets with high‐density grain boundaries (GBs; GB‐rich Bi). The reconstructed GB‐rich Bi catalyst affords a remarkable yield rate of 4.6 mmol h−1 mgcat.−1 and Faradaic efficiency of 32 % for urea production at −0.40 V vs. RHE. Notably, this yield rate is 2 and 8.2 times higher than those of the low‐GB Bi and bulk Bi catalysts, respectively. Theoretical analysis demonstrates that the GB sites significantly reduce the *CO and *NH2 intermediate formation energy and C−N coupling energy barrier, enabling selective urea electrosynthesis on the GB‐rich Bi catalyst. This work will trigger further research into the structure‐activity interplay in dynamic processes using in situ techniques.

Electronic structure-modulated NiFe-metal–organic framework nanosheets for enhance electrochemical oxygen Evolution

Oxygen Evolution Reaction (OER) is a critical half-reaction that hinders water decomposition due to its sluggish kinetics. Developing efficient, stable electrocatalysts for OER is crucial for addressing the challenges in energy crisis and green hydrogen production. Compared to single-metal Metal-Organic Frameworks (MOFs), synergistic interactions between metal ions in bimetallic MOFs provide sufficient space for tuning the electronic structure and oxygen-containing intermediate adsorption energies, and therefore bimetallic MOFs shows great potential in enhancing the OER kinetics. In this work, NiFe-MIL-88A nanosheets were synthesized on nickel foam via a facile one-step hydrothermal method. The catalyst exhibited exceptional OER performance in 1.0 M KOH solution. Notably, it achieved a current density of 50 mA cm−2 at a low overpotential of 220 mV and displayed a Tafel slope of 43.2 mV/dec. Furthermore, it had impressive electrocatalytic durability suitable for commercial applications. This work elucidates the performance enhancement of NiFe bimetallic MOF from the perspective of electron migration. In-situ Raman spectroscopy was adopted to investigate the structural reconfiguration of the catalyst to reveal the true catalytic active sites. First-principle calculation demonstrate that introduction of Ni atoms with low electronegativity is conducive to optimizing the catalytic d-band center and ƒe value. This work provides insights for the designing bimetallic MOFs with superior OER performance.

Ni-Co ternary nitrides with multiple surface oxides as bifunctional oxygen electrocatalysts for metal-air batteries

The bifunctional non-noble metal catalysts based on the metal nitrides with high activity and high efficiency is very challenging for the development of high-performance metal-air batteries. Herein, a new Ni-Co ternary nitrides anchored on nitrogen-doped carbontubes (denoted as NiCoxN/CNT) is rationally designed by the thermal of corresponding hydroxide/carbontubes at low temperature, following nitridation. The synergistic effect between Ni-Co ternary nitrides (Ni4N, Co5.47N, CoN) effectively regulates the electronic configuration of the active site, thereby optimizing the chemisorption energy of the reaction intermediates, resulting in improved intrinsic catalytic activity. The result shows that NiCoxN/CNT not only exhibits excellent half-wave potential of 0.80 V for ORR but also with a low overpotential of 280 mV for OER at 10 mA cm−2, outperforming those of cobalt mononitride and nickel mononitride. Furthermore, Zn-air batteries assembled with NiCoxN/CNT show a high specific capacity of 826.9 mA h g−1 and excellent cycling stabilities up to 190 h in an aqueous electrolyte. More attractively, when assembled into Mg-air batteries, NiCoxN/CNT cathode realizes high power density of 112.38 mWcm−2. Therefore, the design and construction of multiple TMNs is a new guide to break through the bifunctional catalytic activity.

Regulating d-Orbital Hybridization of Subgroup-IVB Single Atoms for Efficient Oxygen Reduction Reaction.

Highly active single-atom electrocatalysts for the oxygen reduction reaction are crucial for improving the energy conversion efficiency, but they suffer from a limited choice of metal centers and unsatisfactory stabilities. Here, this work reports that optimization of the binding energies for reaction intermediates by tuning the d-orbital hybridization with axial groups converts inactive subgroup-IVB (Ti, Zr, Hf) moieties (MN4) into active motifs (MN4O), as confirmed with theoretical calculations. The competition between metal-ligand covalency and metal-intermediate covalency affects the d-p orbital hybridization between the metal site and the intermediates, converting the metal centers into active sites. Subsequently, dispersed single-atom M sites coordinated by nitrogen/oxygen groups have been prepared on graphene (s-M-N/O-C) catalysts on a large-scale with high-energy milling and pyrolysis. Impressively, the s-Hf-N/O-C catalyst with 5.08wt% Hf exhibits a half-wave potential of 0.920V and encouraging performance in a zinc-air battery with an extraordinary cycling life of over 1600h and a large peak power-density of 256.9mW cm-2. This work provides promising single-atom electrocatalysts and principles for preparing other catalysts for the oxygen reduction reaction.

Innovative Catalyst Design of Sea-Urchin-like NiCoP Nanoneedle Arrays Supported on N-Doped Carbon Nanospheres for Enhanced HER Performance.

Hydrogen (H2) stands as a clean energy alternative to fossil fuels, especially within the domain of the hydrogen evolution reaction (HER), offering prospective solutions to mitigate both environmental and energy-related challenges. In this work, we successfully synthesized a sea-urchin-like catalyst, specifically a nickel-cobalt phosphide nanoneedle array on N-doped carbon nanospheres (Ni0.5Co1.5P@NCSs), for efficient HER by a sequential hydrothermal and low-temperature phosphating process. The catalyst exhibits sea-urchin-like structures, offering a specific surface area of 298 m2 g-1 and consequently furnishing a greater abundance of active sites. Comparing with non-sea-urchin-like Ni0.5Co1.5P@CN catalysts, the Ni0.5Co1.5P@NCSs exhibit an overpotential of 163 mV at 10 mA cm-2, a Tafel slope of 60 mV dec-1, and a maintained current density of approximately 90% during 50 h of continuous electrolysis. Experiments demonstrate that the outstanding electrochemical properties of the Ni0.5Co1.5P@NCSs originate from nitrogen doping of carbon spheres, the distinctive morphology of sea-urchin-like nanoneedle arrays, and simultaneous enhancements in intermediate adsorption energy, charge transfer, and electrolyte diffusion channel shortening. This work emphasizes a preparation strategy for synthesizing an attractive electrocatalyst with a low cost and efficient HER performance.

Oxygen vacancies based BiOBr nanoflowers saturable absorber and its application in Q-switched mode-locked infrared laser

In this work, BiOBr nanoflowers with oxygen vacancies as saturable absorber are prepared using hydrothermal method. Passively Q-switched mode-locked infrared laser is achieved. The output power reaches the maximum 312 mW. The minimum Q-switched envelope is 242 ns with the maximum repetition rate of 180.5 kHz. Meanwhile, the mode-locked pulse duration within the Q-switched envelope is approximately 315 ps with repetition rate of 232 MHz. The results of X-ray diffraction (XRD), Electron paramagnetic resonance (EPR), UV–Vis–NIR diffuse reflectance spectra, and X-ray photoelectron spectroscopy (XPS) demonstrate the oxygen vacancies introduce intermediate energy levels in the energy band of BiOBr, which enhances the optical absorption in the near-infrared region. Therefore, BiOBr saturable absorber exhibits good saturable absorption characteristics in the near-infrared region and is a promising modulation element in Q-switched mode-locked infrared lasers.

Efficient BiVO4 Photoanode with an Excellent Hole Transport Layer of CuSCN for Solar Water Oxidation

AbstractBismuth vanadate (BiVO4) is reported as a key material in photoelectrocatalysis owing to high theoretical efficiency, relatively narrow band gap of 2.4 eV, and favorable conduction band edge position for hydrogen evolution. However, the sluggish hole transport dynamics lead to slow photogenerated charge separation and transport efficiencies, which result in charge recombination due to aggregation. Herein, a novel hole transport layer of copper(I) thiocyanate (CuSCN) with the aim of significantly enhancing the efficiency of charge transport and stability of BiVO4 photoanodes is reported. The introduction of the hole transport layer could provide an appropriate intermediate energy level for photogenerated hole transfer and avoid charge recombination and trapping. After a photoassisted electrodeposition process of NiCoFe‐Bi catalysis, the obtained photoanode achieves a photocurrent density of 5.6 mA cm−2 at 1.23 V versus reversible hydrogen electrode under AM 1.5 G simulated solar radiation, and an applied bias photon to current efficiency of 2.31%. With the CuSCN layer, BiVO4 photoanode presented impressive stable photocurrent during 50 h continuous illumination. Meanwhile, the unbiased tandem device of the NiCoFe‐Bi/CuSCN/BiVO4 photoanode and the Si solar cell exhibit a solar‐to‐hydrogen efficiency of 5.75% and excellent stability for 14 h.

Engineering the Electronic Interaction Between Single Au Atoms and CoN Through Nitrogen‐Coordination Bonding as an Efficient Bifunctional Electrocatalyst for Rechargeable Zn–Air Batteries

AbstractSingle‐atom catalysts hold significance in the field of electrocatalysis. In this study, cobalt nitride (CoN), known for its semiconductor characteristics, is selected as the substrate, on which single gold (Au) atoms are loaded, to synthesize the catalyst Au SAC CoN@NF with Au single atoms anchored on CoN catalysts and grown on nickel foam. The introduction of single Au atoms results in an exceptional double‐layer capacitance (1425.7 mF cm−2), which offers immense possibilities for the applications of zinc–air batteries based on Au SAC CoN@NF. The zinc–air batteries demonstrated remarkable performance metrics, including a power density of 161.94 mW cm−2, a specific capacity of 813.80 mAh g−1, and a cycling stability of more than 260 h at 10 mA cm−2. In addition, these batteries show an outstanding round‐trip efficiency of 65.1%. Density functional theory calculations reveal that Au SAC CoN@NF can optimize the adsorption energies of intermediates for oxygen evolution reaction and promote single Au atoms in transporting electrons to the OH− species at an Au–N active site for oxygen reduction reaction. The proposed electronic metal‐support interaction strategy offers fresh insights for designing single‐atom catalysts to enhance electrocatalysis efficiency, thereby expanding the practical application prospects of zinc–air batteries.