Sn-doped Co–P-based trifunctional electrocatalysts for accelerating water splitting and hydrogen generation concurrent with ethylene glycol electrooxidation

Abstract

Hydrogen (H₂) production via water electrolysis is crucial for meeting future energy demands but developing highly active electrocatalysts through simple and quick methods remains challenging. We introduce highly active, stable trifunctional Sn-doped Co–P (Sn-Co–P-x; where x represents % of Sn in the system), fabricated using the electrodeposition technique which possesses superior hydrogen evolution reaction (HER) activity, with a significantly low overpotential of 40 mV and remarkable oxygen evolution reaction (OER) efficiency with an overpotential of 220 mV at 10 mA cm⁻². This catalyst outperforms commercial HER (Pt/C) and OER (IrO₂) catalysts at higher current densities. Sn-Co–P-5 requires a cell voltage of 1.51 V to reach a current density of 10 mA cm⁻² during water splitting. Moreover, H₂ production is further boosted by replacing the OER with the oxidation of ethylene glycol (EG), and a cell voltage of 1.32 V is achieved at 10 mA cm⁻². Theoretical insights confirm that incorporating Sn into the Co–P system facilitates water adsorption and H₂ evolution, attributed to the heightened positive charge on the Co atoms. The downshift of the d-band center in the Sn-Co–P system as compared to Co–P facilitates hydrogen desorption and enhances the overall water-splitting process. This work shows great potential for developing innovative and highly efficient trifunctional electrocatalysts for future applications.