A Rational Design of Cu 2 O−SnO 2 Core‐Shell Catalyst for Highly Selective CO 2 ‐to‐CO Conversion

The electrochemical reduction of CO 2 (CO 2 RR) is a versatile method that is capable of simultaneously reduce CO 2 emission and produce valuable fuels and chemicals. However, its application is hindered by the lack of cost‐effective catalysts and significant overpotential requirement. In this work, we report a low‐cost and surfactant/capping agent free method to synthesize cubic Cu 2 O−SnO 2 core‐shell electrocatalyst, whose thickness can be easily controlled by the content of tin precursor. The optimized Cu 2 O−SnO 2 catalyst with a 5 nm‐thick shell achieved over 90 % faradaic efficiency towards CO at a low overpotential of 390 mV, which is comparable to some of the noble metal catalysts. The catalyst also exhibited good stability over 18 hours of test at −0.6 V vs. RHE in 0.5 M KHCO 3 electrolyte . This work provides a widely applicable strategy for developing a low‐cost electrocatalyst for CO 2 conversion.