Conjugated nickel phthalocyanine polymer selectively catalyzes CO2-to-CO conversion in a wide operating potential window

Abstract Electrochemical CO2 reduction driven by intermittent renewable energy sources is usually limited by output voltage fluctuation caused by their spatial and temporal discontinuities of those renewable energy sources. The development of high-performance catalysts with large current density and high selectivity for the target products in a wide operating potential window is of great importance for utilizing intermittent renewable electricity for CO2 reduction. Herein, we report a two-dimensional (2D) Ni phthalocyanine polymer (NiPcP) that displays superior catalytic activity and high selectivity for CO2-to-CO conversion with a Faradaic efficiency (FECO) over 98% in a wide operating potential window from –0.15 to –0.60 V and a maximum current density of 236 mA cm–2 at –0.6 V. At an overpotential of 0.39 V, NiPcP delivers a nearly 100% FE of CO production, a large CO current density of 197 mA cm–2 and an impressive TOF of 23148 h–1. Experimental and theoretical results disclose that the inherent electronic structure of Ni units, conjugated nature and hydrophobicity of NiPcP promote the CO2RR to CO production and restrain the competitive hydrogen evolution reaction, thereby enhancing the catalytic activity and selectivity for CO2-to-CO conversion. This work emphasizes the importance of modulating the structure and hydrophobicity of nanostructured catalysts for enhancing CO2RR performance.