Induced Diffusion Effect Realizes Heterogeneous Separation/Aggregation for In Situ Fabrication of Heterostructure with Enhanced Catalytic Activity

Abstract

Space charge transfer, which can be provided by heterogeneous structure, is the key to efficient electrocatalytic processes. However, difficulty in controlling the relative atomic diffusion rates due to different atomic radii and affinity makes heterogeneous nanostructures difficult to be accurately designed. Herein, an induced diffusion strategy based on affinity differences between elements is proposed to direct the separation/aggregation of different components in the precursor. The key to strategy in this study is the different affinity of Cu and Co to S/P in the precursor of CuCo Prussian blue analogue (PBA). By controlling the molar ratio of S and P during the phosphorization/vulcanization process, induced diffusion can be achieved and leads to directional separation/aggregation of Cu and Co species. As a result, a heterogeneous yolk‐shell Cu2S@CoP2‐C‐N‐S structure is successfully synthesized with a reticular CoP2‐C‐N‐Cu‐S as the shell and a Cu2S nanocrystal as the core. The space charge effect of the semiconductor heterojunction resulting from component separation/aggregation significantly promotes oxygen evolution reaction, resulting in an ultralow overpotential of 180 mV at 10 mA·cm−2. This work not only provides a simple method for efficient separation of key components in gas‐solid systems but also provides a method for fine‐tuning the active site in an active‐site‐engineering approach.