Nanostructured manganese oxide on carbon for water oxidation: New findings and challenges

Water-oxidation reaction (WOR) is a sluggish reaction for hydrogen production through water splitting. Herein, Mn oxide/mesoporous carbon (MC) is introduced as an active WOR catalyst under neutral conditions. The composite was synthesized through the reaction of permanganate and MC using a simple and low-cost procedure and characterized by scanning electron microscopy, in situ visible spectroscopy, energy-dispersive spectroscopy, (high-resolution) transmission electron microscopy, and X-ray diffraction. Then, the WOR activity of this composite was investigated under neutral conditions. The experiment shows that nanosized Mn oxide/MC is a promising catalyst for water-splitting systems. The overpotentials for the onset (based on the Tafel plot) and 1.0 mA of WOR are 700 and 940 mV, respectively. Based on the LSV, the Tafel slope is 378.6 mV per decade.