Synthesis and application for overall water splitting of transition metal-mixed mesoporous Ta oxide

Cu- and Ni-mixed mesoporous Ta oxides were synthesized by the optimized ligand-assisted templating method, using metal alkoxides and octadecylamine surfactant. The resulting solids were colored due to the presence of Cu or Ni even after the removal of the surfactant. Cu-mixed mesoporous Ta oxide had high BET surface area (330 m2 g−1) and a narrow pore size distribution at 3.3 nm. BET surface area of Ni-mixed mesoporous Ta oxide was 230 m2 g−1, although the pore size distribution tailed in the micropore range with two broad peaks at 2.8 and 1.1 nm. Consequently, about half of the pore volume was occupied by micropores. Ni-mixed mesoporous Ta oxide decomposed water into stoichiometric H2 and O2 under ultraviolet irradiation, while Cu-mixed mesoporous Ta oxide evolved H2 alone.