Efficient charge separation and transportation using 1D iron-sulfide@titania heterojunctions as photoanodes for improved interface stability and photoelectrochemical activity to produce hydrogen

Abstract

1D FeS–FeS₂@TiO₂ heterojunctions were developed to investigate the photoexcited charge separation and transportation to active sites for improved photocatalytic properties. Morphological, optical, and spectroscopic studies on the photoanodes demonstrated excellent interfacial interaction, homogeneity, and wide solar light sequestering. Photoelectrochemical studies optimized the sensitizer loading of the 10-FeS–FeS₂@TiO₂ heterojunction that possesses the highest photocurrent of 1.74 mA cm⁻² as compared to pure TiO₂ NTs with a photocurrent of 0.30 mA cm⁻² at 0.3 V versus Ag/AgCl (1.23 V RHE) under a light intensity of 100 mW cm⁻². Also, 10-FeS–FeS₂@TiO₂ NTs showed an excellent charge carrier donor density (N_D) of 3.86 × 10¹⁷ cm⁻³ and consequently the least electron–hole (e⁻/h⁺) pair recombination was observed. Redox shuttling of FeS–FeS₂ with high surface area TiO₂ NTs resulted in excellent electron–hole pair charge separation and transportation via the optimized loading and uniformity of the sensitizer. The current strategy has paved the way for the development of efficient photocatalysts for enhanced photoexcited charge separation and transportation during photocatalysis.