Coordination Engineering of Ultra-Uniform Ruthenium Nanoclusters as Efficient Multifunctional Catalysts for Zinc–Air Batteries

Abstract

The lack of highly efficient, inexpensive catalysts severely hinders the large-scale application of electrochemical energy conversion technologies (e.g., electrochemical hydrogen evolution reaction (HER) for hydrogen production, metal–air batteries (Cathode: oxygen reduction reaction (ORR))). As a new class of nanomaterials with a high ratio of surface atoms and tunable composition and electronic structure, metal nanocluster (NCs) are promising candidates as catalysts. Herein, a novel catalyst using S,N-doped carbon matrix (NSCSs) is synthesized to efficiently stabilize high density and ultra-uniform ruthenium (Ru) nanoclusters (Ru@NSCSs) by small-molecule self-assembly pyrolysis approach. The obtained Ru@NSCSs catalyst exhibits outstanding HER activity in all pH conditions (especially with a low overpotential of 5 mV at a current density of 10 mA cm−2 in 1 m KOH) and excellent ORR performance (half-wave potential (E 1/2) of 0.854 V in 0.1 m KOH). Based on the experimental investigations and theoretical calculations, it is discovered that the S-atom can modulate the electronic structure and optimization of redox states on the surficial sites of Ru NCs during the ORR process. This work provides a feasible strategy for understanding and regulating the metal–support interface of ultra-uniform nanoclusters catalysts.