Controlled synthesis of high-performance silver/silver orthophosphate (Ag/Ag3PO4) interfaced photoanode with porous tetrahedrons layer for photoelectrochemical water splitting

In this study, a novel interfaced photoanode of silver/silver orthophosphate (Ag/Ag3PO4) was synthesised via the controlled oxidation of Ag foil which resulted in a top porous layer of {111} facets-bounded Ag3PO4 tetrahedrons layer. This was achieved through a systematic understanding and optimisation of the critical synthesis parameters, including: concentration ratio of polyvinylpyrrolidone (PVP) used as the capping agent to precursor (C/P), volume ratio of hydrogen peroxide (H2O2) to deionised water (H2O) (H2O2:H2O) and reaction time. It was revealed that the best-performing Ag/Ag3PO4 interfaced photoanode can be synthesised at the C/P ratio of 4, H2O2:H2O ratio of 3:5 and reaction time of 20 h. This is owing to the synergistic reaction of Ag foil, NaH2PO4 and H2O2 under the assistance of PVP, which leads to the formation of the porous layer of highly reactive {111} facets-bounded Ag3PO4 tetrahedron structures. The optimised Ag/Ag3PO4 interfaced photoanode achieved an unprecedentedly high photocurrent density of 4.19 mA/cm2 at 1 V vs Ag/AgCl with an accompanying measured H2 evolution rate of 49.08 µmol/h cm2. Additionally, the applied bias photon-to-current efficiency (ABPE) and incident photon-to-current efficiency (IPCE) for the Ag/Ag3PO4 interfaced photoanode were recorded at 0.55% (0.84 V vs Ag/AgCl) and 56.5% (1 V vs Ag/AgCl, 410 nm), respectively. [Display omitted] •Facile solution-processed method was used to synthesise Ag/Ag3PO4 photoanode.•Systematic deconstructed insights into the critical Ag/Ag3PO4 synthesis parameters.•Optimal porous {111} facets-bounded Ag3PO4 layer yielded exceptional PEC activity.•Highest photocurrent for bare Ag3PO4 photoanode of 4.19 mA/cm2 at 100 mW/cm2.