Self-driving photothermal anode electrocatalyst towards the robust OER for water electrolysis

Abstract

The hydrogen production of water electrolysis is a potential technique route of clean energy exchange, but suffering from the sluggish oxygen evolution reaction (OER) owing to its four-electron step. In this work, we presented a significant improvement in the OER activity by photothermally triggering P-doped NiFe2O4 (NFO–P) electrocatalyst. As compared to the NiFe2O4 (NFO) catalyst, the excellent PEC performance of robust NFO–P is a result of more readliy generated active sites (Ni(III)), evidencing by the in-situ Raman spectra and polarization curves. With the near-infrared (λ = 808 nm) irradiation, the NFO–P surface temperature increases from 37 to 73 °C, and the NFO–P delivers a current density of 10 mA cm−2 at a pretty low overpotential of 191 mV (10 W/cm2), outperforms most OER catalysts including noble oxides. Photothermal enhancement in OER is attributed to photogenerated hot carriers and thermal activation. The thermal effect accelerates the kinetics, while with the assistance of the hot carrier, the rate-determining step (RDS) transforms from the O* to OOH* formation, reducing the activation energy. This study offers a thorough understanding of the combined contributions of hot carriers and thermal effects to the OER and also opens avenues for enhancing electrochemical efficiency and diminishing techno-economic costs in future applications.