Innovative approach to solar hydrogen generation using SnO2 photocatalyst in water splitting

Abstract

This research explores the capabilities of SnO₂ thin films in renewable energy, with a focus on hydrogen generation through photoelectrochemical (PEC) water splitting. X-ray diffraction (XRD) analysis identifies a tetragonal rutile crystal structure, indicating a highly crystalline phase free from secondary phases. A crystallite size of about 40 nm, determined via the Debye–Scherrer formula, suggests enhanced catalytic suitability for PEC applications. Scanning electron microscopy (SEM) reveals a web-like, rough surface, beneficial for water splitting by providing a high surface area that improves light absorption and charge transfer. The interconnected SnO₂ nanoparticles, averaging 28.63 nm in size, create active sites that further boost photocatalytic performance. UV-Vis spectroscopy shows strong absorption in the UV range (300–330 nm) with limited visible light absorption, consistent with a wide bandgap of approximately 3.63 eV. With 72.5% transparency in the visible spectrum, SnO₂ proves effective as a transparent conducting oxide (TCO), advantageous in optoelectronic devices. Electrochemical impedance spectroscopy (EIS) highlights low charge transfer resistance, and linear sweep voltammetry (LSV) reveals significant photocurrent density, supporting SnO₂'s effectiveness in PEC applications. The solar-to-hydrogen (STH) efficiency is 3.526% at 0.8 V, demonstrating SnO₂'s proficiency in hydrogen production. Additionally, chronoamperometry confirms the film's stability and light responsiveness. A high hydrogen production rate of 3256.93 mol/g over 6 h is attributed to the porous structure of the film, which enhances light harvesting and the hydrogen evolution reaction. These findings establish SnO₂ thin films as a promising material for hydrogen generation and renewable energy applications.