Valence State Modulation of Chromium in Selective Hydrogen Peroxide Production Electrocatalysts

Hydrogen peroxide (H2O2) is a worthy chemical substance with comprehensive applications, but its practical industrial methods involve complex and energy-consuming procedures. Electrocatalytic oxygen reduction for the production of H2O2 is a flexible alternative strategy, which requires a low-cost catalyst with high activity and selectivity for the 2e– ORR pathway. Here, we first present a straightforward and universal one-step hydrothermal method that directly combines Cr-ABIm with commercial carbon black (BP2000) to prepare H2O2 electrochemically with high selectivity and energy saving. A variety of characterization analyses display that the introduction of Cr-ABIm increases the number of defects and active sites and also enlarges the surface area of the catalyst for electrochemical reactions. Importantly, the valence state of Cr is changed (Cr3+ of Cr-ABIm converted to Cr5+) when Cr-ABIm anchors on BP2000, which accelerates the activity of the reduction reaction. The selectivity of the catalyst for H2O2 preparation is also determined by Koutecky–Levich analysis and rotating ring disk electrochemical tests. In a potential range of 0.2–0.7 V (vs reversible hydrogen electrode (RHE)), the electron transfer number of the Cr-ABIm@BP2000 catalyst is on the verge of 2.5, and the electrogenerated yield of H2O2 is 65%. In addition, its mass activity at 0.5 V is up to 7.56 A g–1. Density functional theory (DFT) calculations clarify that suitable N, O coordination on the active surface of BP2000s acquires the changing capacity of the valence state of Cr, thereby regulating the adsorption of intermediate products and endowing it with superior H2O2 performance. It is believed that Cr-ABIm@BP2000 will be a viable electrocatalyst for sustainable in situ generation of H2O2 from oxygen.