Urotropine-triggered multi-reactive sites in carbon nanotubes towards efficient electrochemical hydrogen peroxide synthesis

Abstract

The production of hydrogen peroxide (H2O2) by electrochemical oxygen reduction is a clean and convenient route. Here, we develop a universal urotropine (hexamethylenetetramine) modified carbon-based catalyst strategy. Both experimental results and theoretical calculations proved that the introduction of urotropine not only provides the isolating O2 active sites to protect OOH* from being further split, but also excites carbon nanotube matrix to produce rich secondary O2 active sites. More importantly, the end-on type of adsorption of O2 on excited secondary reactive sites can be stabilized by the hydrogen bond effect, which greatly increases the productivity of H2O2. As a result, the urotropine (hexamethylenetetramine) modified commercial carbon nanotubes (denoted as H-CNTs) catalyst achieved 95% selectivity and 748 mmol·gcatalyst·h−1 yield of H2O2 at 0.7 V vs. RHE. Therefore, this work provides a highly potential urotropine modification strategy towards efficient electrochemical H2O2 synthesis.