Indium Cyanamide for Industrial-Grade CO 2 Electroreduction to Formic Acid.

Developing industrial-grade electroreduction of CO 2 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 CO 2 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 ∼125 mA cm -2 for 160 h. The excellent activity and stability of InNCN are attributed to its unique structural features, including strongly σ-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 CO 2 reduction, broadening the variety of CO 2 reduction catalysts and the understanding of structure-activity relationships.