Self-Assembly of Hydroxyl Metal-Organic Polyhedra and Polymer into Cu-Based Hollow Spheres for Product-Selective CO2 Electroreduction

The electrochemical CO2 reduction reaction (CO2RR), an elegant solution to mitigate the greenhouse effect and produce high-value feedstock, has significant hurdles in selective production of target products. Herein, a series of Cu-based hollow spheres is synthesized through the self-assembly of hydroxyl metal-organic polyhedra and a polymer. The obtained materials with tunable morphology and compositions enable precise generation of varied products in a flow cell. Specifically, polymer-induced sol-gel (PISG)-3 shows 61.1% (-0.9 V, -143 mA cm(-2)) Faradaic efficiency (FE) of C2H4 and negligible CH4, higher than that of PISG-1 (FEC2H4 46.7%) with solid-sphere morphology. Interestingly, the products can be well tuned from C2H4 to CH4 by introducing CaCO3, along with increased hydrocarbon selectivity and CO2 reduction efficiency. Notably, PISG-8 with modified composition displays drastically changed products (FECH4 55.8% and FEC2H4 22.2%, -162 mA cm(-2), -0.9 V). As certified by density functional theory calculations, CaCO3 is proven to decrease the possibility for coexistence of two adjacent *CHO to restrain the dimerization process and enhance the CH4 selectivity.

Automated summary

This research addresses the challenges in selective production of target products in CO2RR by synthesizing Cu-based hollow spheres, allowing for precise generation of various products. The introduction of CaCO3 enables effective tuning of products from C2H4 to CH4, increasing hydrocarbon selectivity and CO2 reduction efficiency.