Cocatalyst-Free and Highly Crystalline Sb2S3 Nanorods for Enhanced Hydrogen Yield Under Sunlight

Abstract

Hydrogen (H₂) production through the photocatalytic process of semiconductors is a promising way to turn solar energy into chemical energy. In recent times, host semiconductors are coupled with a variety of cocatalysts to improve photon absorption, facilitate fast charge carrier separation and transportation, and boost surface catalytic activity. Herein, we synthesized cocatalyst-free and pristine Sb₂S₃ nanorods using a simple hydrothermal method at an optimal temperature of 180 °C for different time durations from 3 to 6 h. The pristine Sb₂S₃ nanorods were comprehensively investigated for microstructural quality and quantity features using XRD, Raman, XPS, EDS, SEM, and TEM. Optical and photocatalyst charge carrier kinetics were studied using UV–Vis spectrophotometer, photoluminescence, and EIS studies. The surface area studies were conducted on Sb₂S₃ nanorods using Brunauer–Emmett–Teller (BET) analysis, and finally, photocatalytic hydrogen evolution tests were performed using gas chromatography (GC). The synthesis time has a significant impact on crystallinity, leading to improved structural and morphological properties with time. Specifically, Sb₂S₃ nanorods synthesized over 6 h exhibit an enhanced specific surface area of 7.52 m²/g and a pore size of 2.3 nm. The 6 h Sb₂S₃ nanorods exhibit a relatively longer lifetime (36 ms), indicating low recombination rate of photogenerated carriers, and promote efficient catalytic water splitting. The high specific surface area, low-intensity photoluminescence peak, less charge transfer resistance, and high transient photocurrent response of 6 h Sb₂S₃ nanorods, indicating that the enhanced synthesis time facilitates faster e^–-h⁺ separation and provides a larger surface area with a number of active sites. Under optimal conditions, the 6 h pristine Sb₂S₃ nanorods have demonstrated a high H₂ yield of 16.89 μmol·h^–1 for this material.