Metal-Ion (Fe, V, Co, and Ni)-Doped MnO2 Ultrathin Nanosheets Supported on Carbon Fiber Paper for the Oxygen Evolution Reaction

Manganese dioxides (MnO2) are considered one of the most attractive materials as an oxygen evolution reaction (OER) electrode due to its low cost, natural abundance, easy synthesis, and environmental friendliness. Here, metal-ion (Fe, V, Co, and Ni)-doped MnO2 ultrathin nanosheets electrodeposited on carbon fiber paper (CFP) are fabricated using a facile anodic co-electrodeposition method. A high density of nanoclusters is observed on the surface of the carbon fibers consisting of doped MnO2 ultrathin nanosheets with an approximate thickness of 5 nm. It is confirmed that the metal ions (Fe, V, Co, and Ni) are doped into MnO2, improving the conductivity of MnO2. The doped MnO2 ultrathin nanosheet/CFP and the IrO2/CFP composite electrodes for OER achieve a low overpotential of 390 and 245 mV to reach 10 mA cm(-2) in 1 m KOH, respectively. The potential of the doped composite electrode for long-term OER at a constant current density of 20 mA cm(-2) is much lower than that of the pure MnO2 composite electrode.