Photocatalytic Hydrogen Production from Biomass Under Solar Irradiation

Abstract

This study aimed at finding ways to harvest hydrogen as sustainable fuel from renewable source using clean and abundant solar energy. Sawdust, a renewable and waste material was used for H2 production, which categorises the harvested hydrogen as ‘green hydrogen’. Initial hydrothermal valorisation of sawdust yielded us cellulose, which was used as the sacrificial agent. Sacrificial agent was then photo-reformed to hydrogen using photocatalyst TiO2 photodeposited with Au, coated with rGO. TiO2, Au and rGO being non-toxic and environmentally friendly didn’t hamper the ‘green’ hydrogen production. TiO2, a semiconductor has band gap of approximately 3.2 eV, which renders it an effective photocatalyst. Nevertheless, its effectiveness is hindered by the rapid recombination of electron-hole pairs. To overcome this, Au of (1,3,5) wt. percentage was photo-deposited onto TiO2, as metal deposition enhances charge separation. Au also exhibits surface plasmon resonance (SPR), improving light absorption. Among the different loadings tested, 3% Au proved to be the most effective, increasing efficiency without obstructing active sites. Modification of metal loaded photocatalyst with rGO, which is conductive material with π conjugation, helps in further reduction in recombination of electron and holes, this increases the photocatalytic activity, with its best performing wt. % was 10% rGO out of 5, 10 & 12 wt. % rGO on 3% Au-TiO2. Furthermore, the use of biomass, sawdust as sacrificial agent is great aid for activity enhancement, as it is oxidised by photo-generated holes which reduces the recombination rate also increasing the quantum yield of photo-catalytically produced green H2. The research successfully illustrated biomass photo-reforming into green hydrogen, yield up to 296.12 mmol, as verified by gas chromatography.