Integration of LaCo(OH)<i><sub>x</sub></i> Photo-Electrocatalyst and Plasmonic Gold Nanoparticles with Sb-Doped TiO<sub>2</sub> Nanorods for Photoelectrochemical Water Oxidation
Debashish Pal, Ayan Sarkar, Nani Gopal Ghosh, Devendra Mayurdhwaj Sanke, Dipanjan Maity, Keshab Karmakar, Debasish Sarkar, Sanjio S. Zade, Gobinda Gopal Khan
Abstract
This work demonstrates a strategic nanoengineering design of a TiO2 nanorod (NR)-based photoanode. Here, the doping of Sb in TiO2 NRs along with co-integration of plasmonic gold nanoparticles and an amorphous lanthanum-cobalt double hydroxide (LaCo(OH)x) oxygen evolution catalyst (OEC) is found to improve visible-light absorption, rapid electron–hole pair separation, fast electron transportation, and the surface photocatalytic reaction of the photoanode, resulting in the ameliorated water oxidation performance. The Sb-doped TiO2 NRs exhibit a reduced band gap, improved photoconductivity, and an excellent photocurrent density (1.03 mA·cm–2 at 1.23 V vs reversible hydrogen electrode (RHE)). The anchoring of Au nanoparticles on Sb-TiO2 NRs significantly improves visible-light absorption and the photocurrent density because of the localized surface plasmon resonance effect. Herein, LaCo(OH)x is demonstrated as a photo-electrocatalyst and incorporated with a TiO2 NR-based photoanode for the first time. Integration of a suitable amount of the LaCo(OH)x OEC with Au/Sb-TiO2 NRs significantly improves photocarrier separation, photogenerated charge transportation, and the surface photo-electrocatalytic reaction and reduces the charge transfer resistance, delivering above 10 mA/cm2 photocurrent density at 2.06 V vs RHE and resulting in the enhanced photoelectrochemical (PEC) activity and photostability for water oxidation. The LaCo(OH)x-electrodeposited Au/Sb-TiO2 NR sample exhibits a hydrogen production rate of 21.4 μmol·cm–2·h–1 at the counter electrode under illumination. This work demonstrates a strategic design of a TiO2-based photoanode integrating doping with plasmonic nanostructures and cocatalysts for solar fuel production through water splitting.