Polarized few-layer g-C₃N₄ as metal-free electrocatalyst for highly efficient reduction of CO₂

The greenhouse effect and global warming are serious problems because the increasing global demand for fossil fuels has led to a rapid rise in greenhouse gas exhaust emissions in the atmosphere and disruptive changes in climate. As a major contributor, CO₂ has attracted much attention from scientists, who have attempted to convert it into useful products by electrochemical or photoelectrochemical reduction methods. Facile design of efficient but inexpensive and abundant catalysts to convert CO₂ into fuels or valuable chemical products is essential for materials chemistry and catalysis in addressing global climate change as well as the energy crisis. Herein, we show that two-dimensional fewlayer graphitic carbon nitride (g-C₃N₄) can function as an efficient metal-free electrocatalyst for selective reduction of CO₂ to CO at low overpotentials with a high Faradaic efficiency of ~ 80%. The polarized surface of ultrathin g-C₃N₄ layers (thickness: ~ 1 nm), with a more reductive conduction band, yields excellent electrochemical activity for CO₂ reduction.