Unravelling the role of interface of CuOx-TiO2 hybrid metal oxide in enhancement of oxygen reduction reaction performance

Abstract

Energy security and clean energy are of increasing importance given the current scenario. Hence fuel cells and metal-air batteries are gaining significant attention in recent times. However, the major problem associated with these technologies is the sluggish nature of oxygen reduction reaction (ORR) and the expense associated with the catalyst. This study reports nitrogen-doped carbon-supported CuOx/TiO2-based heterostructure (CuOx/TiO2-10 wt%/NC-800) as an efficient, durable, and low-cost ORR catalyst. CuOx/TiO2-10 wt%/NC-800 catalyst is synthesized using a simple hydrothermal method. The ORR experiments are performed in an alkaline medium (0.1 M KOH). The catalyst has excellent ORR activity with onset potential and half-wave potential of 0.90 V and 0.80 V vs. RHE, respectively. It also shows outstanding limiting current density of 5.80 mA cm−2. The catalyst offers excellent stability (with 92% current retention after 24 h) and durability (only 25 mV half-wave potential shift after 2000 CV cycles). The catalyst follows the 4e− transfer process (n = 3.94) with rather nominal amount of hydrogen peroxide formation (3.5%). The enhanced ORR activity is attributed to the strong synergistic effect between CuOx/TiO2 and NC. The unique structure formation also helps to get excellent electronic conductivity, large surface area, appropriate porosity, and desirable interface charge transfer between CuOx and TiO2.