AU nanoparticles on in2s3/in2o3 nanopyramids increase photoanodic activity in photoelectrochemical water splitting

Abstract

To fulfill the increasing energy demand, photoelectrochemical (PEC) water splitting is an effective approach. For that, it is very important to give rise to efficient photoelectrodes for the PEC water splitting reaction as the anodic reaction is sluggish, and because of that the overall efficiency remains obstructed. In this context, In2S3/In2O3 nanopyramids with exposed (111) facets are developed following a simple hydrothermal method. Further, the effect of Au plasmonic nanoparticles (NPs) on the In2S3/In2O3 nanopyramid surface is investigated. Au NPs are decorated on In2S3/In2O3 nanopyramids by the thermal reduction method. The dipping time of In2S3/In2O3 in a Au-precursor solution is varied to alter the loading amount of Au. Au NPs enhance the light absorption of In2S3/In2O3 nanopyramids effectively from 600 to 800 nm. Furthermore, in the presence of Au NPs, carrier concentration is enhanced at the same time charge as transportation ability is also enhanced at the interface. The optimum decoration of Au NPs helps to achieve the efficient PEC activity. The best obtained In2S3/In2O3/Au in this study shows enhancement in photocurrent density by generating 5.16 mA/cm2 photocurrent density, which is nearly 3.66 times higher compared to that of In2S3/In2O3 at an applied potential of 0.599 V vs Ag/AgCl. Decoration of Au NPs also leads to a 2.6-fold higher carrier density and cathodic shift in onset potential. In2S3/In2O3/Au achieves a maximum photoconversion efficiency of nearly 1.18% at 0.26 V vs Ag/AgCl in 0.5 M Na2SO4 electrolyte. The In2S3/In2O3/Au nanostructure can even withstand the highly corrosive environment of 3.5% saline water. High photocurrent density of 4.52 mA/cm2 at 0.599 V vs Ag/AgCl can be generated by In2S3/In2O3/Au, where 3.5 wt % saline water is used as electrolyte. The developed photoelectrode: In2S3/In2O3–Au is capable of generating higher photocurrent at 0 V vs Ag/AgCl in 3.5% saline water compared to 0.5 M Na2SO4. Under continuous illumination for 3600 s in saline water, the stability of In2S3/In2O3/Au is observed.