NaBH <sub>4</sub> ‐induced phase transition of CoSe <sub>2</sub> with abundant Se deficiency for acidic oxygen reduction to hydrogen peroxide
Caidi Han, Yong‐Chao Zhang, Qian Zhang, Jinting Wu, Jian Gao, Ji‐Jun Zou, Xiaodong Zhu
Abstract
Abstract Electrocatalytic oxygen reduction (ORR) via the 2e − pathway to form H 2 O 2 in acidic medium has attracted extensive attention. However, the low activity, insufficient selectivity and high cost of catalysts have been the bottlenecks. Herein, CoSe 2 with abundant Se deficiency was synthesized by a simple hydrothermal method, and the addition of NaBH 4 ‐induced CoSe 2 phase transition from orthorhombic to cubic phase with more Se deficiency. The cubic phase CoSe 2 with abundant Se deficiency can effectively regulate the surface electronic structure with suitable binding energies of *OOH and *O, which shows high activity, selectivity and long‐term stability for acidic ORR to H 2 O 2 . The onset potential is as low as 0.73 V vs. reversible hydrogen electrode (RHE), the H 2 O 2 selectivity is 84% (0 V vs. RHE), and the average electron transfer number is about 2.3. Furthermore, the H 2 O 2 yield measured using a flow cell is as high as 115.92 mmol·g cat. −1 ·h −1 and the Faradaic efficiency is 70% at 0 V vs. RHE, which presents high potential in electrocatalytic acidic ORR to H 2 O 2 and organic pollutant degradation using the electron‐Fenton process.