Effects of deposition time on the H2 generation kinetics of electroless-deposited cobalt–phosphorous catalysts from NaBH4 hydrolysis, and its cyclic durability

The effect of electoless-deposition time of a Co–P catalyst on the kinetics of H2 generation in an alkaline NaBH4 solution, and its cyclic durability are investigated. The electroless-deposited Co–P catalyst is composed of both outer spherical Co–P particles and an inner flat Co–P layer. As the deposition time of the Co–P catalyst is increased, the outer spherical Co–P particles grow, and their H2 generation kinetics increase. However, the weight-normalized reaction rates differ as a function of deposition time, although the weight of the deposited material is proportional to the deposition time. Specifically, the Co–P catalyst deposited for 3 min shows the highest weight-normalized H2 generation rate than those deposited for other lengths of time. The rate of H2 generation for the Co–P catalyst is decreased dramatically after one cycle (10 h) due to separation of the Co–P particles from the Co–P plate. Up to the sixth cycle (60 h), the rate of H2 gradually decreases due to a powerful shock on the catalyst support by expansion of H2 volume. Beyond six cycles, the catalytic performance of the Co–P catalyst was stable enough for repetitive use.