Efficient photoelectrochemical H2 generation via electrochemically modified TiO2/electrochemically reduced graphene oxide photoelectrode with Ti3+ defects and Mg(OH)2 nanoplates

•TiO2/ERGO nanocomposites were grown electrochemically on FTO substrate.•TiO2/ERGO photoelectrodes were electrochemically modified with Mg(OH)2 nanoplates and Ti3+defects.•After electrochemical modification, a tenfold increase was observed in photocurrent densities.•The highly efficient photoanode operates without an external power source for PEC H2 production.•The H2 production rate of Mg(OH)2/TiO2/ERGO photoanode reached 24.16 μmol cm−1h−1. This study investigates the electrochemical synthesis and electrochemical modification of a TiO2/Electrochemically reduced graphene oxide (ERGO) photoelectrode to improve its photoelectrochemical efficiency for hydrogen production. TiO2/ERGO nanocomposites were co-electrodeposited on fluorine-doped tin oxide (FTO) substrate. After electrochemical modification of TiO2/ERGO in MgCl2 solution, structural and morphological characterizations revealed that Mg(OH)2 nanoplates formed on the surface, and Mg2+ was doped into the TiO2/ERGO nanocomposite, leading to a formation of Ti3+ defects. Optical characterization revealed a redshift in band gap energy and enhanced absorbance due to Ti3+ defects and Mg(OH)2 nanoplates. The Mg(OH)2/TiO2/ERGO electrode exhibited a tenfold increase in photocurrent densities, reaching 1.20 mA cm−2. The hydrogen production rate reached 24.16 µmol cm−2h−1 without applying external potential and 26.02 µmol cm−2h−1 at an applied potential of 1.0 V. Stability tests showed promising long-term performance, making Mg(OH)2/TiO2/ERGO a potential candidate for photoelectrochemical applications, particularly in H2 generation. [Display omitted]