Aluminum-Doped Reduced Graphene Oxide/TiO ₂ Nanocomposite as Photoelectrodes for Solar-Driven Hydrogen Production and Organic Pollutant Degradation

This study presents an innovative and unbiased photoelectrochemical (PEC) platform based on green electrochemical synthesis and electroreductive Al doping of an electrochemically reduced graphene oxide (ERGO)/TiO 2 nanocomposite, specifically designed for solar-driven hydrogen generation and organic pollutant degradation. Unlike traditional chemical or thermal doping methods, aluminum is incorporated in situ via a mild, environmentally benign electroreductive doping (ERD) strategy, ensuring precise dopant control without external energy inputs or hazardous reagents. The ERGO/TiO 2 photoelectrode was fabricated using a one-step electrochemical codeposition process, highlighting the sustainability and simplicity of this approach. Structural and electronic analyses confirmed anatase TiO 2 with substitutional Al incorporation, evidenced by the (101) peak shift and a reduced interplanar spacing from 0.360 to 0.347 nm. Al doping significantly reduced the optical reflectance, introduced a weak defect/disorder-related absorption tail, suppressed photoluminescence, and lowered the charge-transfer resistance. Under AM 1.5G illumination, the bias-free Al-ERGO/TiO 2 photoelectrode delivered a 24-fold enhancement in photocurrent relative to pristine ERGO/TiO 2, achieving 97.3% methylene blue degradation within 5 h and a hydrogen evolution rate of 10.86 μmol cm –2 h –1 (54.27 μmol cm –2 over 5 h), closely approaching its performance at 1.65 V vs RHE (12.94 μmol cm –2 h –1 ). Radical scavenging experiments identified · OH radicals and photogenerated holes as the dominant oxidative species, with excellent stability over three consecutive cycles.