Efficient CO 2 Reduction to Formate on CsPbI 3 Nanocrystals Wrapped with Reduced Graphene Oxide

Highlights A rational design of metal halide perovskites for achieving efficient CO 2 reduction reaction was demonstrated. The stability of CsPbI 3 perovskite nanocrystal (NCs) in aqueous electrolyte was improved by compositing with reduced graphene oxide (rGO). The CsPbI 3 /rGO catalyst exhibited > 92% Faradaic efficiency toward formate production with high current density which was associated with the synergistic effects between the CsPbI 3 NCs and rGO. Abstract Transformation of greenhouse gas (CO 2 ) into valuable chemicals and fuels is a promising route to address the global issues of climate change and the energy crisis. Metal halide perovskite catalysts have shown their potential in promoting CO 2 reduction reaction (CO 2 RR), however, their low phase stability has limited their application perspective. Herein, we present a reduced graphene oxide (rGO) wrapped CsPbI 3 perovskite nanocrystal (NC) CO 2 RR catalyst (CsPbI 3 /rGO), demonstrating enhanced stability in the aqueous electrolyte. The CsPbI 3 /rGO catalyst exhibited > 92% Faradaic efficiency toward formate production at a CO 2 RR current density of ~ 12.7 mA cm −2 . Comprehensive characterizations revealed the superior performance of the CsPbI 3 /rGO catalyst originated from the synergistic effects between the CsPbI 3 NCs and rGO, i.e., rGO stabilized the α-CsPbI 3 phase and tuned the charge distribution, thus lowered the energy barrier for the protonation process and the formation of *HCOO intermediate, which resulted in high CO 2 RR selectivity toward formate. This work shows a promising strategy to rationally design robust metal halide perovskites for achieving efficient CO 2 RR toward valuable fuels.