SACs on Non-Carbon Substrates: Can They Outperform for Water Splitting?

Abstract

Non-carbon-supported single-atom electrocatalysts (SACs) have attracted tremendous research interest for water splitting, owning to their remarkable differences in bond and coordination, and better and tunable catalytic performance, compared with those carbon-supported SACs and commercial catalysts. The electrocatalytic performance of these non-carbon-supported SACs is intimately related to the structure, surficial chemical groups, and vacancy defects of non-carbon host materials, as well as the physico-chemical properties and population of single atoms. The much widened range of host materials and types of single atoms create virtually limitless opportunities in the design of SACs with tunable structures and electrocatalysis behaviors. In this review, the recent progress of non-carbon-supported SACs for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is visited, where the unique local structures, electrocatalytic performance, catalytic centers and key preparation processes are presented. The characterizations down to atomic scales that can reveal the key local structures and catalytic mechanism are also investigated. New insights into the correlations between the structural evolution of these SACs during electrocatalytic reactions and their catalytic performance are examined. Finally, the major challenges faced by these new SACs are summarized, together with future perspectives on the rational design of superior non-carbon-supported SACs.