Ce-doped Co3O4 nanoplates for photo-assisted methanol electrocatalytic oxidation†
Abstract
The development of advanced efficient and durable non-precious metal-based anode catalysts for photo-assisted direct methanol fuel cells remains a significant challenge. In this study, Ce-doped Co3O4 (Ce–Co3O4) was prepared by a three-step process involving hydrothermal synthesis, cation exchange and calcination. The introduction of Ce can not only induce more Co3+ with oxidation properties, but also expand the light absorption range and improve the separation efficiency of photogenerated electron–hole pairs. In an alkaline solution and under visible light irradiation, Ce–Co3O4 showed high current density (31.4 A g−1), high photo-response current (3.52 A g−1) and good long-term stability (the current density retention was 82% after 13 h under visible light irradiation). The reaction mechanism for the photo-assisted methanol oxidation was investigated by a series of optical characterization studies (UV-vis diffuse reflectance spectroscopy, Mott–Schottky, photoluminescence spectroscopy, and electron paramagnetic resonance). The results indicated that the strong oxidative photogenerated hole (h+), ˙OH, and ˙O2− were beneficial for the oxidation of methanol and COads. This study provides a good idea for the design of efficient non-precious metal based anode catalysts for photo-assisted direct methanol fuel cells.