Surface passivation decoration of amorphous cobalt silicate on molybdenum-doped bismuth vanadate for efficient photoelectrochemical water oxidation

[Display omitted] •A simple method is proposed to prepare Co-Sil/Mo-BiVO4 photoanode.•The photocurrent density of Co-Sil/Mo-BiVO4 is 4.7 times higher than that of BiVO4.•Cobalt species can transfer electron to Mo-BiVO4 to restrain the charge recombination.•Cobalt species is verified to be as the passivation layer. Such a subtly strategy greatly promoted the surface holes consumption rate and made composite photoanode dramatically achieve in 2.82 mA /cm2 at 1.23 VRHE (4.7 - fold higher than BiVO4) with a negative onset potential offset of 207 mV. The amorphous Co - species decoration tremendously enhanced surface charge injection efficiency to almost 90 % at 1.23 VRHE. And the biggest photovoltage and lowest charge recombination kinetics of composite photoanode also presented that the amorphous Co species had the potential ability to be passivation layer which were characterized by OCP and IMPS test.