Tuning the electrochemical properties of a boron and nitrogen codoped nanodiamond rod array to achieve high performance for both electro-oxidation and electro-reduction

Abstract

Design of highly active metal-free electrocatalysts to replace noble metal based materials is crucial for electrocatalysis in various applications. Here we present an efficient and multifunctional metal-free electrocatalyst, vertically aligned boron and nitrogen codoped nanodiamond (VA-BND)/Si rod array (RA). It can achieve high electro-oxidation activity by varying its chemical composition while maintaining superior electro-reduction performance. Methanol oxidation was selected to evaluate its electro-oxidation activity towards small organic molecules in fuel cells. The VA-BND3/Si RA (B/C = 0.015 and N₂ = 1.0%) presented superior methanol oxidation activity with a more negative peak potential compared with commercial Pt/C. Meanwhile, the durability of VA-BND3/Si RA was highly improved relative to that of the Pt/C catalyst. Reduction of refractory organic pollutants, 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47), was chosen to study the electro-reduction activity of VA-BND3/Si RA. The VA-BND3/Si RA was found to be advantageous over the Pd electrode for electro-reduction of BDE-47 in both kinetics and current efficiency at −0.8 V. The excellent electrocatalytic performance of VA-BND/Si RA mainly originated from the doped B and N.