Search

The alkaline hydrogen evolution reaction (HER) for industrial hydrogen generation is a promising way to achieve intermittent energy storage. However, challenges, such as the insufficient supply of adsorbed hydrogen atoms (*H) and slow bubble dynamics, hinder the development of industrial HER. Here, we report a cooperative strategy by leveraging both microscopic enhanced electric field and macroscopic efficient bubble traffic for industrial hydrogen evolution, demonstrated through the NiCoP nanotips on NiP nanorods (NiCoP-tip@NiP). Specifically, during the HER process, the nanotips can accumulate a large number of electrons, enhancing the electric field of the Stern layer. This enhanced electric field accelerates the dissociation of water, resulting in favorable *H for HER. Simultaneously, the confined space between the nanotips hinders the growth of bubbles generated at the tips. Newly formed bubbles will push out the existing bubbles, thus accelerating gas release. As a result, NiCoP-tip@NiP exhibits a low overpotential of 300 mV at 1000 mA cm−2 and maintains stable operation over 90 h at approximately 300 mA cm−2 during HER processes. This cooperative strategy provides profound insights for industrial hydrogen generation. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) activity of Ni-based oxyhydroxides greatly hinges on their phase structures, which are mainly γ and β phases: the former has higher intrinsic activity than the latter. However, it is still a grand challenge to purposefully generate γ phase, rather than β phase. Here, we propose a cation-doping strategy to generate γ phase by taking Zn-doped NiFeP/N-doped C (Z-NFP/N-C) precatalyst as a model. In contrast to the case of NFP/N-C that can only be reconstructed into β-NiFeOOH, Zn dopant will induce the formation of γ-NiFeOOH during an electrochemical process. Specifically, the doped Zn cation will promote the dissolution of NiFeP and redeposition of NiFeOOH on the surface. Simultaneously, the cation defects generated by Zn leaching will force the surrounding Ni valence state to rise for charge balance and will attract more K+ in the solution to intercalate into the interlayer of NiFeOOH, resulting in the formation of γ-NiFeOOH. As a result, the γ-NiFeOOH/Z-NFP/N-C exhibits superior OER performance: a low overpotential of 216 mV at 10 mA cm−2 and satisfactory stability (100 h at 17 mA cm−2). Our study offers a practical approach to produce highly active "true catalyst" for efficient water splitting. [ABSTRACT FROM AUTHOR]

Nickel–iron oxyhydroxides are among the most active electrocatalysts, but their sluggish kinetic of oxygen evolution reaction (OER) limits the energy efficiency toward overall water splitting. Here, we present a "cascade electron transfer" strategy through spurring unidirectional electron transfer among different metal sites in Mn-doped FeNiOOH@FeNiP to boost OER and overall water splitting. The Mn doping induces a cascade electron transfer from Ni to Fe and then to Mn via metal-O-metal bridge, thus promoting the oxidation Ni and Fe centers, which in turn help charge transfer by increasing the covalency between metal-O bonds to optimize the bonding strength between metal and adsorbed oxygen species. Consequently, the optimal Mn–FeNiOOH@FeNiP delivers a fast OER kinetics (32.1 mV dec−1) along with a low overpotential of 215 mV@10 mA cm−2. Benefiting from the synergistic effect of high conductivity, large specific surface area, and favorable OER kinetics, the catalyst only requires a low cell voltage of 1.456 V to achieve 20 mA cm−2 for overall water splitting, superior to that of a commercial RuO2ǁPt/C catalyst. [ABSTRACT FROM AUTHOR]