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Sustainable water electrolysis powered by renewable energy requires cost-efficient, effective, and robust catalysts. This study utilizes NiMoFeO and its nitrogen-doped carbon-coated (NC) derivatives NiMoFe@NC, as advanced OER and HER catalysts, respectively. The derivative fabrication not only simplifies catalyst synthesis but also notably enhances the stability of the HER catalyst through carbon coating. The outstanding OER performance of NiMoFeO is attributed to high-valence metals, while the enhanced HER activity of NiMoFe@NC arises from synergies effect from NiFe and MoO 2. At 10 mA cm−2, NiMoFeO showcased a low OER overpotential of 197 mV, and NiMoFe@NC displayed an extremely low HER overpotential of 8 mV. At 100 mA cm−2 and 27 °C, the NiMoFeO(+)//NiMoFe@NC(−) exhibited a voltage of 1.69 V, outperforming the RuO₂(+)//Pt/C (−) (1.77 V). Notably, over 1000 cycles of repetitive ON/OFF electrolysis, the voltage of NiMoFeO(+)//NiMoFe@NC(−) merely increased 0.01 V, confirming the exceptional potential of these catalysts for hydrogen production compatible with renewable energy. [Display omitted] • Using the same precursor for derivative fabrication simplifies the catalyst synthesis. • NiMoFeO and NiMoFe@NC exhibit significant activity in OER and HER, respectively. • The carbon coating notably enhances HER catalyst stability of NiMoFe@NC. • NiMoFeO(+)//NiMoFe@NC(−) exhibits lower voltage than RuO 2 (+)//Pt/C (−) in the same condition. • NiMoFeO(+)//NiMoFe@NC(−) display outstanding stability during ON/OFF electrolysis. [ABSTRACT FROM AUTHOR]

The combination of a semiconductor heterojunction and oxygen evolution cocatalyst (OEC) is an important strategy to improve photoelectrochemical (PEC) water oxidation. Herein, a novel hamburger-like nanostructure of a triadic photoanode composed of BiVO 4 nanobulks, Co 3 O 4 nanosheets and Ag nanoparticles (NPs), that is, Ag/Co 3 O 4 /BiVO 4 , was designed. In our study, an interlaced 2D ultrathin p-type Co 3 O 4 OEC layer was introduced onto n-type BiVO 4 to form a p-n Co 3 O 4 /BiVO 4 heterojunction with an internal electric field (IEF) in order to facilitate charge transport. Then the modification with Ag NPs can significantly facilitate the separation and transport of photogenerated carriers through the surface plasma resonance (SPR) effect, inhibiting the electron-hole recombination. The resulting Ag/Co 3 O 4 /BiVO 4 photoanodes exhibit largely enhanced PEC water oxidation performance: the photocurrent density of the ternary photoanode reaches up to 1.84 mA cm -2 at 1.23 V vs. RHE, which is 4.60 times higher than that of the pristine BiVO 4 photoanode. The IPCE value is 2.83 times higher than that of the pristine BiVO 4 at 400 nm and the onset potential has a significant cathodic shift of 550 mV for the ternary well-constructed photoanode., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)