Hydrogen production from ammonia borane (AB) is usually governed by water activation, which is not only energy-intensive but also requires expensive and complicated catalysts. We here propose an integrated photocatalytic-photothermal system that dramatically improves water activation and lowers the transport resistance of H2 by means of intermediate state water evaporation. This system is constructed by covering nanocomposites (Cu3P-carbon dots-Cu) upon vertically aligned acetate fibers (VAAFs). As a result of superior hydration effect of VAAFs and local photothermal heating for rapid water evaporation, its hydrogen production efficiency from AB hydrolysis reaches over 10 times the particulate suspension system under solar irradiation. Mechanism analysis reveals that the rapid vaporization of intermediate water promotes the cleavages of O-H bonds in bound water and the adsorption reaction of AB and water molecules at active sites. Therefore, this work provides a novel approach to optimize catalytic reaction in thermodynamics and kinetics for the hydrolysis of AB.
Keywords: Ammonia borane hydrolysis; Hydrogen generation; Photocatalysis; Solar water evaporation; Water activation.