Photoelectrochemical (PEC) water splitting of BiOI{001} nanosheets synthesized by a simple chemical transformation

BiOI nanosheets were successfully prepared by a simple chemical transformation technique. The group theory analysis illustrated that the three vibrational modes (A_1g, B_1g and 3E_g) of BiOI with a tetragonal structure are Raman active, and the A_1g and B_1g bands were found in the observable range. The TEM results signified that BiOI possess a tetragonal crystal structure with exposed {001} facets, which is favorable to aggrandize the visible-light photocatalytic phenomenon. The photocatalytic property of BiOI and the commercial Bi₂O₃ was investigated by the photoelectrochemical (PEC) water splitting process under visible light irradiation. The BiOI produces a photocurrent of 6.56 μA cm⁻² (1.23 V vs. reversible hydrogen electrode (RHE)) for PEC water oxidation at pH 6.6, which is partly attributed to the strong visible light absorbance along a or b direction. The experimental outcome of the ultraviolet photoelectron spectroscopy (UPS) of BiOI exhibited that the holes from the valence band of BiOI can oxidize the water to accomplish an oxygen evolution. - Highlights: • We prepared BiOI {001} by a chemical transformation using commercial bismuth oxide. • BiOI exhibits stronger visible light absorbance in the preferred growth direction. • The PEC water splitting evaluation was demonstrated to be more effective over BiOI than Bi₂O₃. • UPS reveals experimentally the exact VB and CB energy positions of BiOI.