Harnessing the Potential of Morphologically Tailored ZnSn(OH)6 Nanograss Photoanode for Solar-Driven Water Splitting

Abstract

Hydrothermal growth of ZnSn(OH)₆ nanograss on ZnO-coated FTO substrates is demonstrated. Effect of surfactants addition (polyvinylpyrrolidone and polyethylene glycol), precursor concentration, and reaction temperature on surface morphology of ZnSn(OH)₆ nanograss are investigated. Addition of surfactant in precursor solution results in growth of approximately 20–30 nm thick nanograss morphology with varying orientation. The nanograss grow longer by increasing the concentration of precursors solution. The grown ZnSn(OH)₆, exhibits XRD peaks corresponding to cubic phase ZnSn(OH)₆. Optical bandgap of the grown nanograss are calculated in the range from ∼3.0 to 3.5 eV. The nanograss photoanode grown with PEG surfactant (at 200 °C) has shown the highest photocurrent of 2.2 mA/cm² at RHE 1.23V_RHE and photoconversion efficiency of 1.4% at 0.46 V_RHE. The longer nanograss has shown lower charge transfer resistance and higher charge carrier concentration, which is favorable for enhancing the PEC performance.