Electrochemically activated metal oxide sites at Rh–Ni₂P electrocatalyst for efficient alkaline hydrogen evolution reaction

Highly efficient hydrogen evolution reaction (HER) electrocatalysts play a crucial part in generating green hydrogen. Herein, an electrochemical activation approach was applied to design 6.7 Rh–Ni₂P-800CV electrocatalysts in alkaline electrolytes. The results confirm that the generation of metal oxide sites through the electrochemical activation strategy can effectively improve the intrinsic activity of 6.7 Rh–Ni₂P-800CV. The density functional calculations further confirm that metal oxide active sites are favorable for H₂O adsorption and activation and H* adsorption/desorption. The 6.7 Rh–Ni₂P-800CV possesses significantly enhanced HER performance with low overpotential (25 mV at 10 mA·cm⁻²), small Tafel (60 mV·dec⁻¹) and robust stability in 1.0 M KOH, outperforming Pt/C and 6.7 Rh–Ni₂P counterparts. Meanwhile, 6.7 Rh–Ni₂P-800CV can even operate at a large current density (550 mA·cm⁻²) up to 90 h with an overpotential of 320 mV, which meets the requirements of industrial water splitting. What’s more, the overall water-splitting systems (6.7 Rh–Ni₂P-800CV || 6.7 Rh–Ni₂P-800CV) can be directly driven by the solar cell. This work highlights that electrochemical activation technology provides a robust avenue toward constructing efficient electrocatalysts for sustainable energy conversion.