Modulation in d band center of metallic Rh for robust hydrogen evolution reaction

It is generally known that the hydrogen binding strength with active site guarantees the intrinsic catalytic performance toward hydrogen evolution reaction (HER). A moderate binding strength is requirable to achieve a robust HER electrocatalyst. In this work, we report a facile methodology to balance the hydrogen adsorption/desorption capability of metallic Rh by downshift in d band center via a partial sulfurization to construct Rh–Rh2S3 heterostructure. The downshift in d band center of Rh results in weakening the overly strong hydrogen adsorption to a balanced level. Thereby, Rh–Rh2S3 exhibits large decrements (67.2 mV and 92.2 mV) in overpotential at 100 mA cm−2 in acidic HER catalysis than Rh and Rh2S3. Moreover, the merit of modulation in d band center is also reflected by alkaline HER. The overpotential at 100 mA cm−2 for Rh–Rh2S3 is substantially decreased by 117.9 mV and 74.9 mV compared to Rh2S3 and Rh. Additionally, a 3.3-time higher mass activity at −80 mV vs. RHE is achieved for Rh–Rh2S3 with relative to commercial Pt/C.