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• Porous NF/Ni@Co x P y was synthesized via a simple electrodeposition–hydrothermal–thermal phosphorization process. • The in-situ Raman characterization reveals the reconstruction during HER. • The KSCN probing experiment demonstrates the truly active center is Co. • NF/Ni@Co x P y exhibits enhanced activity in acid, buffer and alkaline media. Designing and synthesizing an effective and robust hydrogen evolution reaction (HER) catalyst is of great significance for hydrogen production from electrochemical water splitting yet remains challenge. Herein, this work reports a porous cobalt phosphide nanoneedles arrays grown a coarsen naked nickel foam (NF/Ni@Co x P y) through a successive electrodeposition–hydrothermal–thermal phosphorization process. Detailed investigation reveals the NF/Ni@Co x P y exhibited a porous structure, leading to the largest double-layer capacitance of 7.6 mF cm–2 and enhanced the hydrophily. In addition, the generation Co-P contains both CoP and Co 2 P phases, leading to shift of the electronic structure, together to boost the electrocatalytic HER activity. The NF/Ni@Co x P y only needs overpotential of 77, 98, and 71 mV at 10 mA cm–2 in alkaline, buffer solution, and acid solution, respectively. The SCN– probing experiment and in-situ Raman characterization reveal that the Co serves as the active site and the Co x P y reconstructed to Co(OH) 2 during HER, which accelerating the fast water dissociation, leading to a lower apparent activation energy of 65.9 kJ mol–1. Hence, this study offers a facial synthesis route to prepare catalyst for HER and provides deep insight into the relationship among coarsen substances, microstructures, and electrocatalytic activity. The SCN– probing experiment and in-situ Raman demonstrates the Co serve as the active site during HER. [Display omitted] [ABSTRACT FROM AUTHOR]

• Electrochemical reduction of laser-prepared, in-situ-grown Ti/TiO 2 produced the intermediate layer Ti/TiH 2. • Special structured Mn 3 O 4 @C micro-flakes were prepared by high-temperature pyrolysis-oxidation. Simulated zinc electrowinning tests demonstrated the viability of the Ti/TiH 2 /β-PbO 2 − Mn 3 O 4 @C electrode. • At 50 mA cm−2, Ti/TiH 2 /β-PbO 2 -Mn 3 O 4 @C (0.6 g L−1) exhibited a low overpotential of 493 mV, a low Tafel slope of 73.6 mV dec−1, a low i corr of 2.320×10−5 A cm−2 and voltage stability of 1.65 V vs. RHE for up to 72 h in stability tests" to the original text. Ti-based PbO 2 electrodes must currently address the high overpotential and low corrosiveness of the anodic oxygen evolution reaction (OER) during zinc electrowinning. In this study, a composite electrode composed of Ti/TiH 2 /β-PbO 2 − Mn 3 O 4 @C (0.6 g L–1) was fabricated using Ti/TiH 2 generated by electrochemical reduction of Ti/TiO 2 prepared by laser ablation as an intermediate layer, co-deposited β-PbO 2 , and Mn 3 O 4 @C micro-flakes prepared by high-temperature pyrolysis-oxidation as the active layer. In a zinc electrowinning test solution (50 g L–1 ZnSO 4 mixed with 150 g L–1 H 2 SO 4), the oxygen evolution and corrosion behavior of the obtained Ti/TiH 2 /β-PbO 2 − Mn 3 O 4 @C composite anodes were systematically investigated. Ti/TiH 2 /β-PbO 2 − Mn 3 O 4 @C (0.6 g L–1) exhibited a low overpotential of 493 mV, a low Tafel slope of 73.6 mV dec−1, a low i corr of 2.320 × 10−5 A cm−2 and voltage stability of 1.65 V vs. RHE for up to 72 h in stability tests, with an overall performance outperformed most of the reported Ti-based PbO 2 electrode materials. The outstanding catalytic activity is primarily attributable to the low resistance and porous interlayer of TiH 2 nanosheets, which speeds up the rate of electron transfer. The addition of Mn 3 O 4 @C micro-flakes to the active layer enhances the composite electrode's OER performance and corrosion resistance. [Display omitted] [ABSTRACT FROM AUTHOR]

• The construction of heterostructure at the interface of Cu 2 O and CuNiMo optimized the electronic structure. • The coupling of Cu 2 O with CuNiMo makes Cu 2 O produce a large number of oxygen vacancies, which provided a mass of protons by accelerating water splitting. • The obtained Cu 2 O@CuNiMo exhibits outstanding hydrogen evolution reaction performance with a low overpotential of 49 mV at a current density of 10 mA cm−2 in a 1.0 M KOH electrolyte. • Excellent catalytic performance and stability verified the practical applicability. Electrochemical water splitting is an attractive chemical method for hydrogen generation with cleanliness and zero pollution. However, the reported catalysts are still unsatisfactory due to low electron transport efficiency and poor water splitting capacity. Herein, a high–performance oxygen vacancy–rich Cu 2 O–based heterostructure (Cu 2 O@CuNiMo) was constructed for solving these problems. The results of X–ray photoelectron spectroscopy and Raman suggested that there was strong electron transfer between CuNiMo and Cu 2 O, which could optimize the electronic structure. Electron paramagnetic resonance proved that there were abundant oxygen vacancies (OV S) on the surface of the Cu 2 O, which generated a mass of adsorbed hydrogen (H ads) by accelerating water splitting in an alkaline solution. Therefore, the Cu 2 O@CuNiMo electrocatalyst exhibits outstanding hydrogen evolution reaction (HER) performance with an ultra–low overpotential of 49 mV at a current density of 10 mA cm−2 in 1.0 M KOH electrolyte, outperforming many other previously reported transition metal–based catalysts. Moreover, Cu 2 O@CuNiMo exhibits exceptional durability for a 24–h long–term test at a current density of 200 mA cm−2. This work provides a promising method to design highly active HER electrocatalysts via the dual regulation strategy of oxygen vacancy engineering and electronic behavior. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel hierarchical porous NiSe@Ni 12 P 5 /NCF polymorphs electrocatalyst is first reported. • The prepared NiSe@Ni 12 P 5 /NCF catalyst improve its electrochemical performance through interfacial electron redistribution. • The NiSe@Ni 12 P 5 /NCF catalyst shown best UOR catalytic performance. Electrocatalytic urea oxidation reaction (UOR) is one of the most promising energy-saving alternatives to anodic oxygen evolution reaction (OER), and the development of efficient and stable catalysts for UOR is crucial. Therefore, in this paper, hierarchical structure NiSe@Ni 12 P 5 /NCF with Ni 12 P 5 nanorod arrays coupled with NiSe nanospheres are synthesized on bare nickel-copper foam (NCF) by exogenous phosphorylation and subsequent electrodeposition methods. The catalytic performance of hierarchical structure NiSe@Ni 12 P 5 /NCF in urea-assisted electrolytic water reaction is studied in focus. The results show that the potential of NiSe@Ni 12 P 5 /NCF was only 1.267 V and 1.412 V vs RHE at current densities of 10 mA cm−2 and 100 mA cm−2, respectively, in addition to no significant activity decay after 140 h stability test. This is attributed to the fact that the introduction of NiSe regulated the interfacial charge distribution, creating an interfacial coupling effect that can greatly increase the original catalytic species, as well as the NiOOH species generated during the UOR process as true active sites, which ultimately improving the electrocatalytic UOR performance of NiSe@Ni 12 P 5 /NCF. This study provides a new idea for the preparation of hierarchical selenide - phosphides for electrochemical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • NF-Ni 2 P@NIFe LDH was fabricated, which outperforms the benchmark pair of RuO 2 //Pt/C. • It simultaneously possesses massive active sites and superior intrinsic activity. • Raman and XPS reveals FeOOH and NiOOH severed as active site for HER and OER. Building heterostructures with rich interfaces by surface engineering is one of the most promising approaches to integrating the rich functionalities for water splitting. Herein, the porous and superhydrophilic nickel phosphide@ NiFe bimetal layered double hydroxides (NF-Ni 2 P@NiFe LDH) heterostructure in situ grown on nickel foam was successfully constructed. As a result, the unique of self-supported heterostructure and superhydrophilic surface facilitated electron and mass transfer. In addition, the porous structure promoted active site exposure and was in favor of bubble release. Benefiting from the aforementioned advantages, the NF-Ni 2 P@NiFe LDH performed a superior catalytic performance for water splitting, with a low overpotential of 105.4 mV for hydrogen evolution reaction (HER) and 203.5 mV for oxygen evolution reaction (OER) at 10 mA cm−2, thus a battery voltage of just 1.53 V providing a current density of 10 mA cm−2 at a two-electrode electrolytic cell. Furthermore, the NF-Ni 2 P@NiFe LDH showed a remarkable stability, which worked for over 60 h at 100 mA cm−2 without visible delay. The ex-situ Raman revealed that the NiOOH and FeOOH severed as active site for OER and HER, respectively. [ABSTRACT FROM AUTHOR]

Designing active and durable cost-effective electrocatalysts for catalyzing the oxygen evolution reaction (OER) under a strongly acidic environment is a highly promising approach for OER-associated sustainable energy supplies. Herein, a Pb-Sn-Ca/α-PbO 2 /β-PbO 2 -Mn 2 O 3 (PSC/PbO 2 -Mn 2 O 3) composite electrode is fabricated via a simple two-step process. First, porous Mn 2 O 3 microspheres are synthesized by the solvothermal method. Then, a PSC/PbO 2 -Mn 2 O 3 composite electrode with a special embedded structure is prepared through the introduction of Mn 2 O 3 by composite electrodeposition. The low OER overpotential (621 mV) of the PSC/PbO 2 -Mn 2 O 3 (12 g L −1) composite electrode is reduced by 445 mV compared with that of the industrial Pb-(0.76 wt%) Ag electrode at a current density of 50 mA cm−2. In addition, it shows a service life of up to 91 h at a high operation current density of 1.5 A cm−2 in acidic media (3.06 g L −1H+), which indicates its excellent stability. Therefore, this work not only demonstrates a design for a durable and high-efficiency electrocatalyst for acidic water oxidation but also provides strategies for the synthesis of advanced electrocatalytic electrodes. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction kinetics in industrial zinc electrowinning is sluggish, resulting in low electrocatalytic activity and substantial energy expenditure (about one-third of energy was wasted due to the strong polarization effect). Herein, the paper described a core-shell structured MnCo 2 O 4.5 @C modified PbO 2 electrode through the pyrolysis and co-electrodeposition as a promising candidate for zinc electrowinning. As a result, the obtained Pb-0.2%Ag/ α -PbO 2 / β -PbO 2 -MnCo 2 O 4.5 @C composite electrode showed a sandwich-like structure, where Pb-0.2%Ag as a core, α -PbO 2 as a mid-layer, and β -PbO 2 -MnCo 2 O 4.5 @C served as an electrocatalytic layer. It also possessed improved OER catalytic activity, only required 680 mV to achieve a current density of 50 mA cm−2 and a Tafel slope of 216.04 mV dec−1 in an acidic solution containing 50 g L−1 Zn2+ and 150 g L−1 H 2 SO 4. The current efficiency increased by 0.7% and the cell voltage reduced by 360 mV as compared to a conventional Pb-0.76%Ag alloy electrode, leading to a remarkable energy-consumption reduction of 283.5 kW h for producing per ton metallic zinc. Furthermore, Pb-0.2%Ag/ α -PbO 2 / β -PbO 2 -MnCo 2 O 4.5 @C exhibited a prolonged service life, which worked about 44 h under an ultra-high current density of 2 A cm−2. Hence, this paper provides the strategy to design and construct non-precious, high-performance catalyst for electrolysis and other applications. [Display omitted] • MoCo 2 O 4.5 @C modifying PbO 2 composite electrode was prepared through pyrosis-annealing and electrodeposition. • The overpotential at 50 mA cm−2 of composite electrode was decreased by 353 mV as compared with Pb-0.76%Ag alloy. • The composite electrode had a long service life of 44 h when tested at 2 A cm−2. • As compared to Pb-0.76%Ag alloy, the energy consumption of composite electrode for one-ton zinc was lowered by 283.5 kW h. [ABSTRACT FROM AUTHOR]

The principal factor restricting large‐scale hydrogen production via water electrolysis is the development of inexpensive and efficient catalysts that attain high current densities to produces hydrogen at low potentials. In this study, a series of iron‐based phosphide catalysts (denoted as: PX‐doped Fe/NF) were prepared via one‐step electrodeposition from a eutectic solvent to examine their oxygen evolution reaction (OER) or hydrogen evolution reaction (HER) performance. Notably, P30‐doped Fe/NF forms a porous interconnected nanosheet structure, providing a large active surface areas, abundant active sites and low charge transfer resistance. P30‐doped Fe/NF attained the lowest OER (284.15 mV) and HER (158.17 mV) overpotentials at 10 mA cm−2 in 1.0 M KOH of all the tested catalysts. When used in overall water splitting, the catalyst displayed outstanding adaptability to a range of potentials and current densities. This study provides a facile route for the synthesis of bifunctional transition‐metal phosphide catalysts for the electrolysis of water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zn-VO x -Co 2D ultra-thin nanosheets were developed as electrocatalysts for the first time. • Zn-VO x -Co composed of amorphous and crystalline phase with a heterostructure. • D-band center of metallic Co was optimized by dual-doping Zn and VO x elements. • Zn-VO x -Co revealed high HER activity with nearly 100% Faradaic efficiency. • The electrocatalytic mechanism was proposed based on experimental and DFT calculations. Designing cost-effective catalysts with high-activity and ultra-stability for hydrogen evolution reaction (HER) is important in the scaling-up of water electrolysis process for hydrogen production. Herein, a Zn-VO x -Co two-dimensional (2D) nanosheet with well-integrated heterostructure was successfully synthesized on carbon fiber paper (CFP) by a facile electrodeposition approach. Interestingly, the obtained nanosheets composed of amorphous VO x -Co and Zn-Co crystalline phases with a heterostructure. Density functional theory (DFT) calculations reveled that the dual-doping of Zn and VO x optimized d-band center of Co and balanced adsorption and desorption of H, which enhanced intrinsic electrocatalytic HER activity. As a result, the optimum catalyst achieved a current density of 10 mA cm−2 at an overpotential as low as 46 mV and long-term electrochemical stability over 36 h in 1 M KOH solution. This work opens a new avenue for designing electrocatalysts with unique crystalline-amorphous heterostructure by dual-doping to achieve tunable surface properties as well as d-band structure. [ABSTRACT FROM AUTHOR]