p-Block Bismuth Nanoclusters Sites Activated by Atomically Dispersed Bismuth for Tandem Boosting Electrocatalytic...

Constructing electrocatalysts with p-block elements is generally considered rather challenging owing to their closed d shells. Here for the first time, we present a p-block-element bismuth-based (Bi-based) catalyst with the co-existence of single-atomic Bi sites coordinated with oxygen (O) and sulfur (S) atoms and Bi nanoclusters (Bi_clu ) (collectively denoted as BiOS_SA /Bi_clu ) for the highly selective oxygen reduction reaction (ORR) into hydrogen peroxide (H₂ O₂ ). As a result, BiOS_SA /Bi_clu gives a high H₂ O₂ selectivity of 95 % in rotating ring-disk electrode, and a large current density of 36 mA cm^-2 at 0.15 V vs. RHE, a considerable H₂ O₂ yield of 11.5 mg cm^-2 h^-1 with high H₂ O₂ Faraday efficiency of ∼90 % at 0.3 V vs. RHE and a long-term durability of ∼22 h in H-cell test. Interestingly, the experimental data on site poisoning and theoretical calculations both revealed that, for BiOS_SA /Bi_clu , the catalytic active sites are on the Bi clusters, which are further activated by the atomically dispersed Bi coordinated with O and S atoms. This work demonstrates a new synergistic tandem strategy for advanced p-block-element Bi catalysts featuring atomic-level catalytic sites, and the great potential of rational material design for constructing highly active electrocatalysts based on p-block metals.