Indium Cyanamide for Industrial-Grade CO₂ Electroreduction to Formic Acid

Developing industrial-grade electroreduction of CO2 to produce formate (HCOO-)/formic acid (HCOOH) depends on highly active electrocatalysts. However, structural changes due to the inevitable self-reduction of catalysts result in severe long-term stability issues at industrial-grade current density. Herein, linear cyanamide anion ([NCN](2-))-constructed indium cyanamide nanoparticles (InNCN) were investigated for CO2 reduction to HCOO- with a Faradaic efficiency of up to 96% under a partial current density (j(formate)) of 250 mA cm(-2). Bulk electrolysis at a j(formate) of 400 mA cm(-2) requires only -0.72 V-RHE applied potential with iR correction. It also achieves continuous production of pure HCOOH at similar to 125 mA cm(-2) for 160 h. The excellent activity and stability of InNCN are attributed to its unique structural features, including strongly sigma-donating [NCN](2-) ligands, the potential structural transformation of [N=C=N](2-) and [N C-N](2-), and the open framework structure. This study affirms metal cyanamides as promising novel materials for electrocatalytic CO2 reduction, broadening the variety of CO2 reduction catalysts and the understanding of structure-activity relationships.