Enhanced photoelectrochemical water-splitting performance of SrNbO2N photoanodes by flux-assisted synthesis method and surface defect management
Perovskite SrNbO2N particles were directly synthesized by one-step thermal nitridation method with chloride flux and subsequently annealed under inert Ar flow. By a suitable adjustment of flux synthesis parameters, including nitridation temperature and the composition of molten salt, preferable experimental condition were found to suppress the formation of surface Nb defect, as well as obtaining samples with high crystallinity. The different SrNbO2N photoanodes were fabricated using electrophoretic deposition (EPD) method followed by necking treatment. The SrNbO2N photoanode prepared by optimum experimental condition (nitridation temperature: 850 °C, the molar ratio of flux SrCl2 : KCl = 2:1) exhibits a highest photocurrent density of 2.0 mA·cm-2 at 1.23 VRHE under simulated sunlight (AM 1.5G 100 mW·cm-2) in 1 M NaOH electrolyte. In comparison, the other highly defective SrNbO2N photoanodes shows unsatisfied water oxidation performance, which demonstrates the necessity to reduce the destructive effect of defects in order to achieve higher photocurrent density.