Hydrogen Adsorption Free Energy Research Articles

The electronic properties, stability and catalytic activity of metallofullerene (M@C60) for robust hydrogen evolution reaction: DFT insights

The development of low-cost, and highly active catalysts for electrocatalytic hydrogen evolution process is of great interest. Exohedral first row transition metal doped fullerenes based single atom catalysts (SACs) are expected to replace precious metal catalysts for sustainable and large-scale commercial scalability of hydrogen generation. Herein, a series of ten metal (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu & Zn) single atoms doped C60 fullerenes (metallofullerenes) are screened for hydrogen evolution reaction. All the studied metallofullerenes are optimized with the various possible spin states and the most stable spin states among them are selected for further analysis. The stability of electrocatalysts is evaluated via interaction energy analysis, which reveals that all the designed metallofullerenes are thermodynamically stable (−0.24 to −4.30 eV). The hydrogen adsorption (Eads) and Gibbs free energy results reveal that Fe@C60 complex has the best catalytic activity for hydrogen evolution process with optimal ΔGH value of 0.08 eV. FMO analysis declares appreciable variations in electronic properties of C60 fullerene upon doping. Moreover, density of states (DOS) analysis also corroborates with FMO analysis for designed metallofullerene (M@C60) catalysts and HM@C60 complexes. Exchange current density is plotted as a function free energy (ΔGH) for hydrogen evolution process over designed metallofullerene. The volcano plot reveals the near thermoneutral behavior of Fe@C60 catalyst for hydrogen evolution reaction. Overall, results presented here for systematic screening of potential HER from metallofullerene based single atom catalysis can remarkably contribute to the design and fabrication of electrocatalysts.

Nickel-constructing interfaces of multiheterostructure on self-supporting electrode for efficient overall urea-water splitting

Water splitting is an environmentally friendly strategy for producing hydrogen but is constrained by the high theoretical potential of the oxygen evolution reaction (OER) at the anode. It is possible to save energy by substituting the OER with the urea oxidation reaction (UOR) with a low theoretical potential. In particular, developing bifunctional catalysts (hydrogen evolution reactions (HER)/UOR) and exploring their catalytic mechanisms and active sites are highly desirable with the rapid development of the hydrogen economy. Herein, the combination of electrodeposition and immersion methods to grow a well-aligned MOF on a graphene-like material (MXene) is reported. Specifically, Ni3S2 species were formed on the hexahedral structure of cobalt-based MOF (CoMOF) by electrodeposition. The resultant M/CM/Ni3S2/NF demonstrates good electrocatalytic capabilities toward the HER and UOR, with overpotentials and potentials of 0.174 and 1.392 V required to reach 100 mA cm−2, respectively. DFT results established that the coupling of MXene, CoMOF, and Ni3S2 can optimize the free energy of hydrogen adsorption on the catalyst surface. Furthermore, in situ XRD revealed that the (111), (2¯ 11) and (220) crystal planes resulted in good stability of the material. This work provides an innovative and novel route for designing high-activity bifunctional catalysts for various electrochemical energy applications.

Genetic descriptor search algorithm for predicting hydrogen adsorption free energy of 2D material

Transition metal dichalcogenides (TMDs) have emerged as a promising alternative to noble metals in the field of electrocatalysts for the hydrogen evolution reaction. However, previous attempts using machine learning to predict TMD properties, such as catalytic activity, have been shown to have limitations in their dependence on large amounts of training data and massive computations. Herein, we propose a genetic descriptor search that efficiently identifies a set of descriptors through a genetic algorithm, without requiring intensive calculations. We conducted both quantitative and qualitative experiments on a total of 70 TMDs to predict hydrogen adsorption free energy (Delta G_H) with the generated descriptors. The results demonstrate that the proposed method significantly outperformed the feature extraction methods that are currently widely used in machine learning applications.

Theoretical understanding of two-dimensional boridenes M4/3B2 for hydrogen evolution

Layered boridenes M4/3B2 have been experimentally validated as a rising two-dimensional (2D) material family. Herein, we investigate nine kinds of 2D M4/3B2 (M = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W) toward their structural stabilities, electronic properties, and hydrogen evolution performances based on density functional theory (DFT) calculations. Our results show that except for Cr4/3B2, other 2D M4/3B2 materials are dynamically and kinetically stable and are promising for synthesis and application in hydrogen production. Metallic Ti4/3B2 and Ta4/3B2 monolayers are easily oxidized in aqueous environments as ideal platforms with optimal hydrogen adsorption free energies and exchange current densities around the peak of the activity volcano. Our work provides a systematic guideline for the application of the 2D M4/3B2 family in HER and reveals their underlying electronic origins.

Dual in-plane/out-of-plane Ni2P-BP/MoS2 Mott-Schottky heterostructure for highly efficient hydrogen production

A catalyst innovation with the aim of developing noble-metal-free substitutes is one key aspect for future sustainable hydrogen energy deployment. Herein, we fabricated a dual in-plane/out-of-plane Ni2P-black phosphorus (BP)/MoS2 heterostructure through an all-solution process for the hydrogen evolution reaction (HER). The covalently cross-connected MoS2 and metallic Ni2P-BP interfaces benefit the charge transfer in the electrochemical performances via the Mott-Schottky effect. For the HER, the Ni2P-BP/MoS2 heterostructure shows excellent catalytic activity with a low overpotential of 99 mV at 10 mA cm−2 and a small Tafel slope of 97 mV dec−1 in alkaline electrolyte. The first-principle calculations verify that the work function difference at the Mott-Schottky interface favors electron transfer from Ni2P-BP to outer-surface MoS2 to boost the HER process. Therefore, the Ni2P-BP/MoS2 heterostructure presents near-neutral hydrogen adsorption free energy (ΔGH*, −0.0287 eV), indicating superior HER activity beyond the counterparts (MoS2, BP, and Ni2P-BP). This work inspires possibilities for optimizing BP-based composites through multidimensional interface engineering with the goal of achieving highly efficient hydrogen production electrocatalysis.

Nanoarchitectonics of La‐Doped Ni3S2/MoS2 Hetetostructural Electrocatalysts for Water Electrolysis

MoS2 with 2D structure shows efficient hydrogen evolution reaction (HER) performance because undercoordinated Mo–S edges have ideal hydrogen adsorption free energy. MoS2 usually does not satisfy the bifunctional catalysts because of the poor intrinsic oxygen evolution reaction (OER) catalytic activity. Herein, it is proposed to construct heterostructure with OER active components to induce efficient bifunctional catalytic activity along with heteroatom doping to modify the electronic structure to optimize the adsorption and desorption capabilities of reaction intermediates. La‐doped Ni3S2/MoS2 grown on nickel foam (La‐NMS@NF) is synthesized as bifunctional catalyst taking advantage of the excellent OER performance of Ni3S2. La‐NMS@NF evolves into nanoflower‐like structures with the addition of La dopant, which provides abundant pore channels to facilitate mass transfer and exposure of active sites. Density functional calculations reveal that the La‐doped Ni3S2/MoS2 heterointerface can optimize the water adsorption and H* adsorption/desorption, improving the HER performance. The La‐NMS@NF exhibits an overpotential of 154 and 300 mV for HER and OER at 100 mA cm−2 in 1.0 m KOH. Herein, a heteroatom‐driven heterostructure activation strategy for electron rearrangement and structural evolution in electrocatalysts to decrease energy consumption in overall water splitting is demonstrated.

Modulation of the electronic structure of Co2P by Mo, Fe co-doping for efficient urea electrolysis

Hydrogen production by urea splitting not only plays an energy-saving role in the production of hydrogen energy, but also can purify wastewater containing urea, which has great advantages compared with hydrogen production by water splitting. In this study, Mo, Fe co-doped bifunctional Co2P electrodes were prepared through hydrothermal and moderate-temperature phosphating methods. Under the synergistic effect of bimetallic cations, the electronic structure of Co2P is effectively modulated, thus showing excellent electrochemistry performance in urea splitting. In the electrolyte solution of 1 M KOH and 0.5 M urea, the potential of urea oxidation reaction (UOR) is 1.26V, 1.316 V and 1.336V for driving current density of 10, 50 and 100 mA cm−2, and the overpotential of hydrogen evolution reaction (HER) is 194 mV, 244 mV and 268 mV for driving current density of 10, 50 and 100 mA cm−2. The overall urea electrolysis only requires a voltage of 1.415 V and 1.686 V to drive a current density of 10 and 50 mA cm−2, which is one of the best catalytic activities reported to date. The experimental results show that the increased activity is assigned to the rapid charge transfer, the exposure of more active sites and the improved conductivity due to the doping of bimetallic ions. Density functional theory (DFT) demonstrates that the prepared Mo, Fe co-doped Co2P electrodes has the smallest Gibbs free energy for hydrogen adsorption compared with Fe co-doped Co2P electrodes. This work laid a new foundation for the synthesis of bimetallic cation-doped transition metal phosphide (TMP) for urea-assisted water splitting.

Triangular nanosheet arrays of O-doped Co/Fe disulfides as highly efficient electrocatalysts for the hydrogen evolution reaction

The development of inexpensive and efficient electrocatalysts is of significance for the hydrogen evolution reaction (HER) involved in water splitting. In this work, we report triangular nanosheet arrays of O-doped Co/Fe disulfides (labelled O-(CoFe)S2-x-y, in which x is the Fe concentration and y is the sulfurization temperature) grown on carbon cloth (CC). With the Co-MOF as precursor, Fe was introduced by ligand exchange, and O-doped metal sulfides were achieved via calcination followed by sulfurization. An optimized sample of CC@O-CoFeS-0.025–500 exhibited an outstanding electrocatalytic HER performance, and it showed strong durability (≥ 24 h) and a very low overpotential of 105 mV at a current density of 10 mA cm−2 (η10 = 105 mV) in 0.5 M H2SO4. The interspaces-rich nanosheet array morphology of O-CoFeS-0.025–500 enabled maximum exposure of the electrocatalytically active sites. O doping effectively modulated the electronic structure, promoted charge redistribution of the catalyst and significantly increased the intrinsic catalytic activity. Density functional theory (DFT) calculations indicated that the Co atoms in pure CoS2 were the catalytically active sites, and the Gibbs free energy for hydrogen adsorption (ΔGH*) was 0.38 eV. Most notably, Fe/O codoping changed the active sites of O-CoFeS-0.025–500 from Co to S with a markedly reduced ΔGH* of 0.22 eV at the S sites. This work provides a novel perspective for designing outstanding electrocatalysts through element doping to realize highly effective water splitting and produce hydrogen.

Multilayered NiMo/CoMn/Ni Cathodic Electrodes with Enhanced Activity and Stability toward Alkaline Water Electrolysis.

In this study, multilayered NiMo/CoMn/Ni cathodic electrodes were prepared by the multilayered electrodeposition method. The multilayered structure includes a nickel screen substrate, CoMn nanoparticles at the bottom, and cauliflower-like NiMo nanoparticles at the top. The multilayered electrodes have a lower overpotential, preferable stability, and better electrocatalytic performance than monolayer electrodes. In a three-electrode system, the overpotentials of the multilayered NiMo/CoMn/Ni cathodic electrodes at 10 and 500 mA/cm2 are only 28.7 and 259.1 mV, respectively. The overpotential rise rate of the electrodes after constant current tests at 200 and 500 mA/cm2 was 4.42 and 8.74 mV/h, respectively, and the overpotential rise rate after 1000 cycles of cyclic voltammetry of the electrodes was 1.9 mV/h, while the overpotential rise rate after the three stability tests of the nickel screen was 5.49, 11.42, and 5.1 mV/h. According to the Tafel extrapolation polarization curve, the Ecorr and Icorr of the electrodes were -0.3267 V and 1.954 × 10-5 A/cm2, respectively. The charge transfer rate of the electrodes is slightly slower than that of the monolayer electrodes, indicating that its corrosion resistance is more excellent. An electrolytic cell was designed for the overall water-splitting test, and the current density of the electrodes was 121.6 mA/cm2 at 1.8 V. In addition, the stability of the electrodes is excellent after intermittent testing for 50 h, which can greatly reduce power consumption and is more suitable for industrial overall water-splitting tests. In addition, the three-dimensional model was used to simulate the three-electrode system and alkaline water electrolytic cell system, and the simulation results are consistent with the experimental results. The hydrogen adsorption free energy (ΔGH) of the electrodes was -1.0191 eV, which was evaluated by density functional theory (DFT). The ΔGH is closer to zero than that of the monolayer electrodes, indicating that the surface has stronger adsorption of hydrogen atoms.

Bimetallic single-cluster catalysts anchored on graphdiyne for alkaline hydrogen evolution reaction

Pt-based electrocatalysts suffer from high water dissociation barriers that limit their overall hydrogen evolution reaction (HER) activities in alkaline media. Here we predict the bimetallic four-atom single-cluster catalysts (SCCs) M1A3 (M as later transition metal and A as early transition metal) with pyramidal structure supported on graphdiyne (GDY) for alkaline HER. Theoretical calculations show that the stable Pt1Ti3/GDY SCC delivers high alkaline HER activity via the Volmer-Heyrovsky mechanism. The excellent catalytic performance of Pt1Ti3/GDY SCC is attributed to both the low-valent Pt site that renders an optimal hydrogen adsorption free energy (ΔG*H), and the synergic effect of adjacent Ti sites that leads to a low water dissociation barrier. By screening alternative M1 in M1Ti3/GDY for optimal ΔG*H and facile water dissociation, we further identify the Ir1Ti3/GDY SCC to be a potentially high-performing alkaline HER electrocatalyst at low *OH coverage. Our work provides new insights and guidelines for the rational design of alkaline HER electrocatalysts.

Cold plasma-prepared Ru-based catalysts for boosting plasma-catalytic CO2 methanation

In this work, γ-Al2O3 supported Ru-based catalysts were prepared by cold plasma for boosting plasma-catalytic CO2 methanation without additional heating. CO2 conversion over plasma-prepared Ru/γ-Al2O3 (76.3%) was far superior to Ru/γ-Al2O3-C prepared by thermal reduction (52.0%) due to the high dispersion and surface enrichment of Ru induced by plasma. CoRu/γ-Al2O3 and AuRu/γ-Al2O3 prepared by plasma possessed enhanced and similar plasma-catalytic CO2 methantion activity. The sizes of the metal nanoparticles are small, and the CoRu nanoparticles showed smaller size and higher dispersion than those of AuRu. The AuRu and CoRu alloys were formed in AuRu/γ-Al2O3 and CoRu/γ-Al2O3, and the CoRu showed higher alloying degree and surface enrichment degree. Well alloyed RuCo may reduce the free energy of hydrogen adsorption at the catalysts. Small particle size can improve their atom utilization efficiency, and surface enrichment of the active species can shorten the heterogeneous reaction from 7 to 5 steps.

Binary pyrene-benzene polymer/Znln2S4 S-scheme photocatalyst for enhanced hydrogen evolution and antibiotics degradation

Recently, Step-scheme (S-scheme) photocatalysts possess great prospects because of the unique charge transport route and high efficiency of charge separation in photocatalysis. Herein, binary Znln2S4/pyrene-benzene polymer (ZIS-PyP) S-scheme heterojunction was fabricated by an in-situ method. The resulting ZIS-PyP exhibits an excellent photocatalytic H2 evolution rate of 54 μmol h−1 which is 2.5 and 10.8-fold than pure ZnIn2S4 and PyP, respectively. The trapping agent experiments reveal the main active species are ·O2− and h+ in the TCH degradation reaction. The characteristic experiments and DFT calculations were used to elucidate the photocatalytic mechanism. The average hydrogen adsorption free energy of ZIS-PyP-H is determined to be −1.51 eV, smallest than that of ZIS-H and PyP-H, which indicates the most favorable for hydrogen mass transfer in ZIS-PyP. Driven by band bending, built-in electric field and Coulombic repulsion, a unique electronic transmission along S-scheme route between ZnIn2S4 and PyP was formed. Therefore, the powerful electrons left in the LUMO of PyP and strong holes in VB of ZnIn2S4 attended to reactions, ultimately achieved an optimal hydrogen production and TCH degradation efficiency in ZIS-PyP S-scheme system.

Synergism of NiFe layered double hydroxides/phosphides and Co-NC nanorods array for efficient electrocatalytic water splitting

The green hydrogen route provides a reliable way to reduce dependence on fossil fuels. Hydrogen production by water electrolysis is an efficient way to convert unstable renewable energy sources into hydrogen energy. Herein, a rod-like N-doped carbon nanorods array cooperated with layered double hydroxide (Ni2Fe@Co-NC/CC) and a tri-metal phosphides composite (P-Ni2Fe@Co-NC/CC) is fabricated, which is believed can facilitate the electron and mass transfer efficiency. The Co element in Ni2Fe@Co-NC/CC can promote the formation of high-valence Ni and activate lattice oxygen to form abundant dual OER active sites. While the P-Ni2Fe@Co-NC/CC can obtain optimized hydrogen adsorption free energy due to synergistic effect of trimetallic phosphides and nitrogen-doped carbon structure to promotes the HER progress. Therefore, due to the synergistic effect between metal hydroxide/phosphide and Co-decorated NC nanorods array, low overpotentials of 240 and 137 mV at 100 mA cm−2 can be achieved for OER and HER with excellent electrocatalytic stability. Besides, the Ni2Fe@Co-NC/CC//P-Ni2Fe@Co-NC/CC device can afford cell voltage of 1.579 V at 50 mA cm−2 in water splitting, which demonstrate a new idea for rational designed electrocatalytic water splitting composites towards high activity and stability.

Single-atom doped graphene for hydrogen evolution reactions

Atomic doping is a widely used technique to modify the electronic properties of two-dimensional materials for various applications. In this study, we investigate the catalytic properties of single-atom doped graphene as electrocatalysts for hydrogen evolution reactions (HERs) using first-principles calculations. We consider several elements, including Al, Ga, In, Si, Ge, Sn, P, As, and Sb, which were interstitially doped into single and double C vacancies in graphene. Our density functional theory calculations show that all the considered doped graphene, except for As-doped graphene, can be highly active for HER, with hydrogen adsorption free energies (ΔG H*) close to the optimal value (ΔG H* = 0), ranging from −0.19 to 0.11 eV. Specifically, ΔG H* of Al, Ga, In, and Ge are much closer to zero when doped in the single vacancy than in the double vacancy. In contrast, ΔG H* of Sb and Sn are much closer to zero in the double vacancy. Si and P have ΔG H* values close to the optimum in both vacancies. Interestingly, the vacancy numbers play a crucial role in forming orbital hybridizations, resulting in distinct electronic distributions for most dopants. As a result, a few doped graphenes show distinctive ferrimagnetic and ferromagnetic orders, which is also an important factor for determining the strength of H adsorption. These findings have important implications for designing graphene-based HER catalysis.

First-Principles Study of MoS2, WS2, and NbS2 Quantum Dots: Electronic Properties and Hydrogen Evolution Reaction

The electronic and catalytic properties of two-dimensional MoS2, WS2, and NbS2 quantum dots are investigated using density functional theory investigations. The stability of the considered structures is confirmed by the positive binding energies and the real vibrational frequencies in the infrared spectra. The ab initio molecular dynamics simulations show that these nanodots are thermally stable at 300 K with negligible changes in the potential energy and metal–S bonds. The pristine nanodots are semiconductors with energy gaps ranging from 2.6 to 3 eV. Edge sulfuration significantly decreases the energy gap of MoS2 and WS2 to 1.85 and 0.75 eV, respectively. The decrease is a result of the evolution of low-energy molecular orbitals by the passivating S-atoms. The energy gap of NbS2 is not affected, which could be due to the spin doublet state. Molecular electrostatic potentials reveal that the edge sulfur/transition metal atoms are electrophilic/nucleophilic sites, while the surface atoms are almost neutral sites. MoS2 quantum dots show an interestingly low change in the hydrogen adsorption free energy ~0.007 eV, which makes them competitive for hydrogen evolution catalysts.

Heterojunction regulates the function of coral like NiCoP for efficient hydrogen evolution reaction

The development of earth abundant electrocatalysts for high performance hydrogen evolution reaction (HER) is highly desirable in energy conversion system. Transition metal phosphide has been exploited to promote electrochemical performance due to its unique heterointerface, outstanding conductivity, and a wide pH range tolerance. Herein, we employ a facile hydrothermal approach to build a heterojunction interface modulated coral-like NiCoP electrocatalyst with favorable crystalline surface, minimal charge transfer resistance, and excellent electron transfer for outstanding HER. In alkaline media, the optimum NiCoP electrocatalyst demonstrates excellent HER performance with an overpotential of 215 mV and Tafel slope of 82 mV dec−1 at 10 mA cm−2. This benefits from the formation of heterojunction with exposed active sites, redistributed electrons and altered coordination environment. The combined experimental results and density functional theory (DFT) investigations demonstrate that heterojunction interfaces are beneficial for lowering the Gibbs free energy of hydrogen adsorption (ΔGH∗), hence boosting HER dynamics process. This study presents a feasible approach for the preparation of low-cost, high-efficiency NiCoP electrocatalysts for HER, which is particularly appealing for practical applications.

Joule heating synthesis of well lattice-matched Co2Mo3O8/MoO2 heterointerfaces with greatly improved hydrogen evolution reaction in alkaline seawater electrolysis with 12.4 % STH efficiency

Herein, through a rapid Joule heating method, we have successfully prepared well lattice-matched Co2Mo3O8/MoO2 heterointerfaces on Ni foam (Co2Mo3O8/MoO2/NF) in only 130 s. Notably, the rapid Joule heating can effectively avoid oxidation of catalyst caused by prolonged heating and achieve rich uncoordinated Mo4+ sites, which contributed to the enhanced electrocatalytic performance in hydrogen evolution reaction (HER). As-prepared Co2Mo3O8/MoO2 delivered remarkable HER activity (23 mV at 10 mA cm−2), which was comparable to Pt-based electrocatalyst. As-prepared sample also revealed excellent stability at 200-h test in electrocatalytic splitting of alkaline seawater. Of particular note, the solar-driven H2O-H2 electrolyzer also showed a promising solar-to-hydrogen (STH) efficiency of 12.4 %. The cell voltage for the home-made anion exchange membrane (AEM) seawater electrolyzer was only 2.13 V at 200 mA·cm−2 at 50 °C, and only 4.7 kW-h required to produce 1 m3 of H2. DFT calculations revealed that the electron redistribution spontaneously takes place at Co–O–Mo bonds at Co2Mo3O8/MoO2 heterointerfaces, which could regulate the electronic structure and d-band center of Mo sites, and then achieve high-efficiency adsorption of H2O on Mo sites and near-zero hydrogen-adsorption free energy on O sites. This study provided a new strategy to regulate the chemical states via Joule heating for highly efficient seawater splitting to evolve H2.

Electric double layer-mediated polarization field for optimizing photogenerated carrier dynamics and thermodynamics

Photocatalytic hydrogen evolution efficiency is limited due to unfavorable carrier dynamics and thermodynamic performance. Here, we propose to introduce electronegative molecules to build an electric double layer (EDL) to generate a polarization field instead of the traditional built-in electric field to improve carrier dynamics, and optimize the thermodynamics by regulating the chemical coordination of surface atoms. Based on theoretical simulation, we designed CuNi@EDL and applied it as the cocatalyst of semiconductor photocatalysts, finally achieved a hydrogen evolution rate of 249.6 mmol h−1 g−1 and remained stable after storing under environmental conditions for more than 300 days. The high H2 yield is mainly due to the perfect work function, Fermi level and Gibbs free energy of hydrogen adsorption, improved light absorption ability, enhanced electron transfer dynamics, decreased HER overpotential and effective carrier transfer channel arose by EDL. Here, our work opens up new perspectives for the design and optimization of photosystems.

Work-function-induced electron rearrangement of in-plane FeP@CoP heterojunction enhances all pH range and alkaline seawater hydrogen evolution reaction

Generally, the pH dependence of electrocatalytic hydrogen evolution reaction (HER) often limits its practical application. Herein, we design in-plane FeP@CoP heterojunctions with rich coupling interfaces and unique electronic structures. The 3D self-supporting structure of in-plane FeP@CoP heterojunctions confers high mechanical stability and electrical conductivity. The work function balances the electronic states of FeP and CoP, suggesting that no additional electron loss is required to adjust the Fermi energy. This facilitates the improvement of the interfacial charge distribution state, promotes the adsorption/dissociation of H2O, and reduces the free energy of hydrogen adsorption (ΔGH* = -0.02 eV). In situ Raman spectroscopy under alkalinity revealed the H-down conformation of water, enhancing the binding energy between active site and H, and a favorable OH- adsorption site through catalyst reconfiguration. Therefore, FeP@CoP satisfies the high requirements of HER under different pH conditions, requiring only low overpotentials of 40, 33, 66, and 37 mV to drive 10 mA cm−2 in acidic, alkaline, neutral and alkaline seawater electrolytes, respectively. In particular, the FeP@CoP/CC demonstrates outstanding durability in a wide pH medium and alkaline seawater, indicating the potential for large-scale hydrogen production. This work provides deep insights into inexpensive and efficient in-plane heterojunction catalysts for pH-universal HER.

S, Fe dual doped and precisely regulated CoP porous nanoneedle arrays for efficient hydrogen evolution at 3 A cm−2

Transition metal phosphides (TMPs) have been proved as promising catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, CoP has a strong hydrogen adsorption energy, resulting in a slow Heyrovsky step in the HER. Herein, the solid phase FeS is ionized into S and Fe ions and doped into cobalt precursor during the hydrothermal process based on the precipitation dissolution equilibrium principle, and the doping strategy precisely regulated the atomic ratio of metal/P. The optimized S, Fe-CoP@IF one-dimensional porous nanoneedles structure exhibit excellent HER performance, which only required 82.3 mV and 200.1 mV to achieve 100 mA cm−2 and 3 A cm−2 together with high currents stability for 100 h. It also has better OER performance, with 260 mV reaching 100 mA cm−2. Further simulated industrial test for S, Fe-CoP@IF in alkaline anion-exchange membrane (AEM) cells show that only 1.75 V is required to attain 500 mA cm−2. Density functional theory (DFT) calculations confirmed that the dual-doping further modulates the electronic structure of CoP, reduces the Gibbs free energy for hydrogen adsorption. This work provides the possibility to further improve the catalytic activity of cobalt phosphide and apply it to industrial applications.