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.