Efficient Electrochemical Reduction of Carbon Dioxide to Acetate on Nitrogen-Doped Nanodiamond

Abstract

Electrochemical reduction of CO₂ is an attractive technique for reducing CO₂ emission and converting it into useful chemicals, but it suffers from high overpotential, low efficiency or poor product selectivity. Here, N-doped nanodiamond/Si rod array (NDD/Si RA) was proposed as an efficient nonmetallic electrocatalyst for CO₂ reduction. It preferentially and rapidly converted CO₂ to acetate over formate with an onset potential of −0.36 V (vs RHE), overcoming the usual limitation of low selectivity for C2 products. Moreover, faradic efficiency of 91.2–91.8% has been achieved for CO₂ reduction at −0.8 to −1.0 V. Its superior performance for CO₂ reduction can be attributed to its high overpotential for hydrogen evolution and N doping, where N-sp³C species was highly active for CO₂ reduction. Electrokinetic data and <i>in situ</i> infrared spectrum revealed the main pathway for CO₂ reduction might be CO₂ → CO₂^•– → (COO)₂^• → CH₃COO^–