Preparation of Amorphous SnO2‐Encapsulated Multiphased Crystalline Cu Heterostructures for Highly Efficient CO2 Reduction

Abstract Controlling the architectures and crystal phases of metal@semiconductor heterostructures is very important for modulating their physicochemical properties and enhancing their application performances. Here, a facile one‐pot wet‐chemical method to synthesize three types of amorphous SnO 2 ‐encapsulated crystalline Cu heterostructures, i.e., hemicapsule, yolk–shell, and core–shell nanostructures, in which unconventional crystal phases (e.g., 2H, 4H, and 6H) and defects (e.g., stacking faults and twin boundaries) are observed in the crystalline Cu cores, is reported. The hemicapsule Cu@SnO 2 heterostructures, with voids that not only expose the Cu core with unconventional phases but also retain the interface between Cu and SnO 2 , show an excellent electrocatalytic CO 2 reduction reaction (CO 2 RR) selectivity toward the production of CO and formate with high Faradaic efficiency (FE) above 90% in a wide potential window from −1.05 to −1.55 V (vs reversible hydrogen electrode (RHE)), and the highest FE of CO 2 RR (95.3%) is obtained at −1.45 V (vs RHE). This work opens up a new way for the synthesis of new heterostructured nanomaterials with promising catalytic application.