Moving beyond bimetallic-alloy to single-atom dimer atomic-interface for all-pH hydrogen evolution
Ashwani Kumar, Viet Q. Bui, Jinsun Lee, Lingling Wang, Amol R. Jadhav, Xinghui Liu, Xiaodong Shao, Yang Liu, Jianmin Yu, Yosep Hwang, Huong Thi Bui, Sara Ajmal, Min Gyu Kim, Seong‐Gon Kim, Gyeong‐Su Park, Yoshiyuki Kawazoe, Hyoyoung Lee
Abstract
Abstract Single-atom-catalysts (SACs) afford a fascinating activity with respect to other nanomaterials for hydrogen evolution reaction (HER), yet the simplicity of single-atom center limits its further modification and utilization. Obtaining bimetallic single-atom-dimer (SAD) structures can reform the electronic structure of SACs with added atomic-level synergistic effect, further improving HER kinetics beyond SACs. However, the synthesis and identification of such SAD structure remains conceptually challenging. Herein, systematic first-principle screening reveals that the synergistic interaction at the NiCo-SAD atomic interface can upshift the d-band center, thereby, facilitate rapid water-dissociation and optimal proton adsorption, accelerating alkaline/acidic HER kinetics. Inspired by theoretical predictions, we develop a facile strategy to obtain NiCo-SAD on N-doped carbon (NiCo-SAD-NC) via in-situ trapping of metal ions followed by pyrolysis with precisely controlled N-moieties. X-ray absorption spectroscopy indicates the emergence of Ni-Co coordination at the atomic-level. The obtained NiCo-SAD-NC exhibits exceptional pH-universal HER-activity, demanding only 54.7 and 61 mV overpotentials at −10 mA cm −2 in acidic and alkaline media, respectively. This work provides a facile synthetic strategy for SAD catalysts and sheds light on the fundamentals of structure-activity relationships for future applications.