A cost-effective indium/carbon catalyst for highly efficient electrocatalytic reduction of CO2 to HCOOH

A highly efficient electrocatalyst is a key factor in CO2 conversion using electrochemical methods. Although the single metal catalyst is a key electrocatalyst, its broader application is seriously hindered when it demonstrates unsatisfactory performance. Consequently, how to tune the catalytic capacity of single metal catalysts is an urgent issue that needs to be resolved. In this study, a series of single metal In/C catalysts were synthesized using NaBH4 as a reducing agent, and it was found that the content and crystallinity of In (0) depended on the as-used structure directing agents. Electrochemical tests showed that In/C (CT) synthesized by adding CTAB could effectively reduce CO2 to formic acid with a high Faraday efficiency (89%) of HCOOH at -0.61 V vs. RHE. In the meantime, it presented superior stability during 10 h electrolysis. It was interesting to find that In/C (CA) and In/C (ET) also exhibited better catalytic performance in a wide potential range, which indicated that the crystallinity of indium obviously affected the selectivity and activity during the reduction of CO2 to HCOOH. Furthermore, lower crystallinity of In (0) in In/C (CA) and In/C (ET) led to more efficient catalytic properties in a wide potential range.