Combined effects of annealing treatment and compounding with FeOOH cocatalyst on efficiency and stability of BiVO4/Ag3PO4 photoanode

Bismuth vanadate (BiVO 4 ) is a promising metal oxide photoabsorber for photoanode applications but is limited by its relatively short hole diffusion length resulting in severe charge complexation and limited performance. Herein, Ag 3 PO 4 was compounded on BiVO 4 through photodeposition of Ag followed by solution oxidation. The annealing of the composite BiVO 4 /Ag 3 PO 4 heterojunction at 400 °C precipitated some Ag from Ag 3 PO 4 on BiVO 4 /Ag 3 PO 4 to form a new ternary photoanode BiVO 4 /Ag 3 PO 4 /Ag. Compared to the unannealed sample, the light trapping and crystal quality enhanced, resulting in increased photocurrent density of the annealed BiVO 4 /Ag 3 PO 4 photoanode (4.46 mA cm −2 ) by 59.9 % when compared to the unannealed photoanode (2.79 mA cm −2 ). To further optimize the photoanode, co-catalyst iron hydroxyl oxide (FeOOH) was deposited to yield BiVO 4 /Ag 3 PO 4 /Ag/FeOOH photoanode with maximum photocurrent density of 4.71 mA cm −2 at 1.23 V (vs. reversible hydrogen electrode, V RHE ), equivalent to about 3.7-fold the value of BiVO 4 photoanode. The photoanode maintained 90.8 % of its initial current density after 3 h stability tests. Besides, the photoelectrocatalytic degradation of Rhodamine B pollutant by BiVO 4 /Ag 3 PO 4 /Ag and BiVO 4 /Ag 3 PO 4 /Ag/FeOOH photoanode showed performance enhancement when compared to BiVO 4 /Ag 3 PO 4 . Overall, the proposed strategy looks very promising for the rational fabrication of high-efficiency heterojunction photoanodes.