Photoelectrocatalytic hydrolysis of ammonia borane by electrochemical deposited cuprous oxide on titanium dioxide nanotube arrays

Photoelectrocatalytic hydrolysis of ammonia borane (AB) is a promising technique for producing hydrogen gas (H2) in the presence of an appropriate photocatalyst under light irradiation and bias. The application of cuprous oxide on titanium dioxide nanotube arrays (Cu2O/TNA) for the photoelectrocatalytic hydrolysis of AB was studied. Cu2O/TNA exhibited a spectral response in the ultraviolet–visible region and an onset wavelength of 600 nm. With AB in an electrolyte, Cu2O/TNA exhibited a significant increase in its photocurrent spectral response at a bias of 0.1 V versus Ag/AgCl. The H2 generation rate by photoelectrocatalysis (under 5-mW cm−2 irradiation at 455 nm; bias of 0.1 V vs. Ag/AgCl) was 0.018 μmol s−1 cm−2, which was twice that by photocatalysis and four times those by catalysis and electrocatalysis; a Faradaic efficiency of 77% (corresponding to the oxidation reaction of AB) was also observed. Hence, Cu2O/TNA is an efficient photoanode for photoelectrocatalytic hydrolysis of AB.