Efficient photoelectrochemical H₂ generation via electrochemically modified TiO₂/electrochemically reduced graphene oxide photoelectrode with Ti<SUP>3+</SUP> defects and Mg(OH)₂ nanoplates

This study investigates the electrochemical synthesis and electrochemical modification of a TiO2/Electrochem- 2 /Electrochem- ically reduced graphene oxide (ERGO) photoelectrode to improve its photoelectrochemical efficiency for hydrogen production. TiO2/ERGO 2 /ERGO nanocomposites were co-electrodeposited on fluorine-doped tin oxide (FTO) substrate. After electrochemical modification of TiO2/ERGO 2 /ERGO in MgCl2 2 solution, structural and morphological characterizations revealed that Mg(OH)2 2 nanoplates formed on the surface, and Mg2+ 2+ was doped into the TiO2/ 2 / ERGO nanocomposite, leading to a formation of Ti3+ 3+ defects. Optical characterization revealed a redshift in band gap energy and enhanced absorbance due to Ti3+ 3+ defects and Mg(OH)2 2 nanoplates. The Mg(OH)2/TiO2/ERGO 2 /TiO 2 /ERGO electrode exhibited a tenfold increase in photocurrent densities, reaching 1.20 mA cm-- 2 . The hydrogen production rate reached 24.16 mu mol cm-- 2 h- 1 without applying external potential and 26.02 mu mol cm-- 2 h- 1 at an applied potential of 1.0 V. Stability tests showed promising long-term performance, making Mg(OH)2/TiO2/ 2 /TiO 2 / ERGO a potential candidate for photoelectrochemical applications, particularly in H2 2 generation.