Efficient CO₂ Reduction to Formate on CsPbI₃ Nanocrystals Wrapped with Reduced Graphene Oxide

HIGHLIGHTS: A rational design of metal halide perovskites for achieving efficient CO₂ reduction reaction was demonstrated. The stability of CsPbI₃ perovskite nanocrystal (NCs) in aqueous electrolyte was improved by compositing with reduced graphene oxide (rGO). The CsPbI₃/rGO catalyst exhibited > 92% Faradaic efficiency toward formate production with high current density which was associated with the synergistic effects between the CsPbI₃ NCs and rGO. ABSTRACT: Transformation of greenhouse gas (CO₂) 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 CO₂ reduction reaction (CO₂RR), however, their low phase stability has limited their application perspective. Herein, we present a reduced graphene oxide (rGO) wrapped CsPbI₃ perovskite nanocrystal (NC) CO₂RR catalyst (CsPbI₃/rGO), demonstrating enhanced stability in the aqueous electrolyte. The CsPbI₃/rGO catalyst exhibited > 92% Faradaic efficiency toward formate production at a CO2RR current density of ~ 12.7 mA cm−2. Comprehensive characterizations revealed the superior performance of the CsPbI₃/rGO catalyst originated from the synergistic effects between the CsPbI₃ NCs and rGO, i.e., rGO stabilized the α-CsPbI₃ 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 CO₂RR selectivity toward formate. This work shows a promising strategy to rationally design robust metal halide perovskites for achieving efficient CO₂RR toward valuable fuels.