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[Display omitted] Enhancing the electrocatalytic oxygen evolution reaction (OER) performance is essential to realize practical energy-saving water electrolysis and CO 2 electroreduction. Herein, we report a bimetallic co-doping engineering to design and fabricate nickel–cobalt-iron collaborative oxy-hydroxide on nickel foam that labeled as NiCoFeO x H y -NF. As expected, NiCoFeO x H y -NF exhibits an outstanding OER activity with current density of 10 mA cm−2 at 194 mV, Tafel slope of 53 mV dec−1, along with the robust long-term stability, which is significantly better than bimetallic NiCo and NiFe combinations. Comprehensive computational simulations and characterizations jointly unveil that the twisted ligand environment induced by heteroatoms ensures the balance strength between the metal–oxygen hybrid orbital states and the oxidized intermediates adsorption, thus lowering the oxygen cycling energy barriers for overcoming the sluggish OER kinetics. Moreover, a novel phase transition behavior is monitored by in-situ Raman spectra under OER operating conditions, which facilitates electron-mass transfer as well as boosts the exposure of activity sites. For practical applications, Ni 2 P-NF || NiCoFeO x H y -NF and Cu || NiCoFeO x H y -NF couples were constructed to realize high-efficiency water electrolysis and CO 2 electrochemical reduction for the production of valuable H 2 and C 2 H 4 , respectively. This work elucidates a novel mechanism by which bimetallic co-doping improves the electrocatalytic OER activity of nickel-based hydroxides. [ABSTRACT FROM AUTHOR]

With the scarcity of fuel energy, non-noble metal compounds assisted water of electrolysis is becoming a potential candidate for cost-effective and high-quality hydrogen production. To date, transition metal phosphide (TMP) has been considered as one of the most promising catalysts for water splitting because of its multitudinous but controlled constituent elements and stoichiometric ratios. In this review, the electronic structure analysis of TMP dialectically reveals the active derivation for catalyzing hydrogen evolution (HER) and oxygen evolution reaction (OER). And then the strategies of rationally designing the structure and composition of electrocatalyst to improve its intrinsic activity are discussed, especially interface engineering. Besides, this review also focuses on the negligible stability issue during the water splitting process. In the end, some key challenges and research orientations of TMPs are pointed out, which is instructive for developing high-efficient and stable electrocatalysts for water splitting. • The activity derivation of transition metal phosphide (TMP) for water splitting. • Optimization strategies for TMPs to modulate their electron structure. • Strategies to improve conductivity and durability for the first time. • Prospects for the development of the design and synthesis of TMP in water splitting. [ABSTRACT FROM AUTHOR]

Developing transitional metal-based electrocatalysts with outstanding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance is essential for energy-efficiency alkaline water electrolysis. Herein, a group of heterostructured electrocatalysts constructing of nickel-based hydroxide (NiX(OH) x , X = Co, Fe) nanosheets decorated on copper phosphide nanowires arrays，were fabricated. Both of the as-prepared NiCo(OH) x -CuP/CF and NiFe(OH) x -CuP/CF present outstanding HER and OER activity, with the overpotential of 79 and 202 mV to deliver 10 mA cm−2, respectively, along with considerable long-term stability. Encouragingly, the NiCo(OH) x -CuP/CF ǀǀ NiFe(OH) x -CuP/CF couple enables sustainable alkaline water electrolysis and powered by a solar-powered system. In-depth analyses elucidate that owing to the modulated heterogeneous interfacial states, both of the catalytic kinetics can be optimized targeting HER and OER, respectively. More significantly, a regulated electrode-electrolyte microenvironment induced by unique arrays nanostructure efficiently promote the electron-mass transfer capacity, thereby facilitating the catalytic activity expression. This work demonstrates the desirable catalytic performance by rationally designing of hydroxide-phosphide heterostructure, and highlights the structural features on catalytic performance promotion. • A delicate NiCo(OH) x -CuP/CF and NiFe(OH) x -CuP/CF catalysts were fabricated, in which the heterogeneous interfacial synergy effect between copper phosphide and nickel-based hydroxide enables the catalytic performance breakthrough. • The modulation of current distribution for the HER and OER optimizing the reaction kinetics, is achieved by interfacial synergy effect between Cu 3 P and nickel-based hydroxide. • The arrays nanostructure features high active area, good electrical conductivity, while also regulate the interfacial microenvironment between electrocatalysts and electrolyte that facilitates electro-mass transfer. [ABSTRACT FROM AUTHOR]