Interfacial electronic interaction regulation of Rh2P by combining N, P co-doped graphene for boosting hydrogen evolution reaction

Abstract

Hydrogen evolution reaction (HER) is a fundamental half reaction for electrolytic water splitting, which has an important effect on the efficiency of hydrogen production. Pt is considered as the best HER electrocatalyst but hindered by its high cost and scarcity. Developing highly active electrocatalyst for HER is quite significant for advancing the development of hydrogen energy technologies. Here, well-dispersed and ultrafine Rh2P nanoparticles are successfully embedded in N, P co-doped graphene (NPG) by a facile and environmental-friendly pyrolysis method, endowing the electrocatalyst to achieve superior HER electrochemical performance in both acid and alkaline electrolyte. Rh2P@NPG-150 shows a splendid HER activity with small overpotentials of 28.6 and 13.6 mV for arriving 10 mA cm−2 in acid and alkaline electrolyte, respectively, which surpass the catalytic activity of the commercial Pt/C. The Rh2P@NPG-150 also demonstrates a robust HER stability and its V-t curve holds quite stable under electrolysis at 20 and 50 mA cm−2 for 25 h in both acid and alkaline electrolyte. As revealed by density functional theory calculations and XPS characterizations, owing to the incorporation of P into Rh, the d band center of Rh2P moves up, resulting in decrease of the number of electrons filled in the antibonding orbital, thus facilitating the adsorption of hydrogen atoms. Moreover, the charge density difference of Rh2P@NPG further reveals that there is strong interfacial electron interaction between Rh2P and NPG, which optimizes the hydrogen binding energy (close to zero) and promotes its charge transfer during HER process.