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 a highly active, stable trifunctional Sn-doped Co-P (Sn-Co-P-x; where x represents % of Sn into 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 having overpotentials of 220 mV at 10 mA/cm2. This catalyst outperforms commercial HER (Pt/C) and OER (IrO2) catalysts at higher current densities. The Sn-Co-P-5 achieves a cell voltage of 1.51 V to reach a current density of 10 mA/cm2 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/cm2. 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.