Electrochemical Reduction and Hydrogenation of Co Oxides

摘要

The electrochemical hydrogenation properties of CoO and Co_3O_4 powders were investigated and compared to those of hexagonal close-packed Co. The discharge capacity was measured in KOH aqueous solution under a controlled current density 500 mA/g. The maximum reversible discharge capacities of Co, CoO, and Co_3O_4 were 415 mAh/g (2 h charging), 389 mAh/g (2 h charging), and 426 mAh/g (5 h charging), equivalent to COH_(0.91), COH_(0.85), and CoH_(0.93), respectively. Because CoO and Co_3O_4 are mostly reduced to Co in the initial charge stage, the discharge capacities of both oxides are mainly from dehydrogenation of CoH_x.