Self-assembled metal cluster/perovskite catalysts for efficient acidic hydrogen production with an ultra-low overpotential of 62 mV and over 1500 hours of stability at 1 A cm−2

Abstract

The production of green hydrogen as a promising form of clean energy via water splitting relies on the development of efficient and stable electrocatalysts for the hydrogen evolution reaction (HER). Herein, we present a new electrocatalyst, Ca₂CoRuO₆ (CCRO), that exhibited a record low overpotential of 62 mV at a high current density of 1 A cm⁻² and the smallest Tafel slope of 10 mV dec⁻¹ (vs. more than 400 mV at 1 A cm⁻² and 29 mV dec⁻¹ of commercial Pt/C). Moreover, the CCRO catalyst maintains stable performance for over 1500 hours in a proton exchange membrane electrolyzer operating at a current density of 1 A cm⁻². In situ X-ray absorption, Raman, and X-ray diffraction spectroscopies indicated a two-step in situ transformation of CCRO. The pristine form of CCRO was reduced from Ru⁵⁺/Co³⁺ to Ru³⁺/Co²⁺ within the first few hours under HER conditions. Subsequently, the catalyst slowly self-assembled to form Ru metal nanoclusters doped with Co (denoted as Co–Ru) on top of the CCRO substrate (Co–Ru/CCRO). First-principles calculations revealed that the synergistic effect within the Co–Ru cluster and hydrogen spillover from the metal cluster to the interface between Co–Ru and CCRO contribute to its outstanding hydrogen production performance. This work presents a new promising HER catalyst with record HER activity and reveals an unusual in situ reconstruction process for the catalyst.