Design and Optimization of Chromium-Based Polymeric Catalysts for Selective Electrocatalytic Synthesis of Hydrogen Peroxide
Huiying Meng, Wen Luo, Yang Wu, Yifan Zhang
Abstract
In this study, we designed and synthesized a series of chromium-based polymers (Cr-Ps) and their composites using oxidized carbon nanotubes (O-CNTs) through one-pot ligand engineering. The H2O2 production capacity of Cr-Ps increased with an increasing ratio of C–O and Cr–O bonds, which is consistent with the trend observed in the Cr-Ps@O-CNT. The addition of O-CNTs during Cr-Ps synthesis led to a dense structure, which enhanced the electron donor effect and effectively improved the selectivity of the materials for the electrocatalytic production of H2O2. Furthermore, during the modulation of different ligands, we observed that the polymers and their complexes formed with terephthalic acid ligands containing para-carboxyl groups had the highest coordination activity and selectivity. The Cr-BDC@O-CNT, using terephthalic acid as the ligand, had the highest C–O and Cr–O densities, resulting in an H2O2 yield of 87% in an alkaline solution and an electron transfer number of about 2.2. Compared with Cr-BDC without O-CNTs, its selectivity increased by 32%, due to the higher number of C–O and Cr–O bonds in its dense structure. Moreover, the mass activity of the Cr-BDC@O-CNT reached 19.42 A g−1 at 0.2 V and the Faraday efficiency reached up to 94%, demonstrating excellent electroreduction activity. Our work provides insight into the design of efficient H2O2 electrocatalysts through ligand engineering, opening up new ideas for future research.