Solar photo-catalytic production of hydrogen by irradiation of cobalt co-doped TiO2

Abstract

Cobalt (Co) co-doped TiO2 photocatalysts (P–Cs) with differing mass fractions of Co (% wt.) were synthesized, characterized, and evaluated toward the solar photocatalytic production of hydrogen (SP–CPOH) from a pure electron donors (EDs), industrial wastewater (IWW), and municipal wastewater (MWW). The improvements in the photocatalytic properties of TiO2 by adding Co were followed and subsequently related to the production of hydrogen (POH). The tests were conducted in a liquid phase solar pilot-plant (LPSPP) with a compound parabolic collector (CPC) configuration. The addition of Co to the lattice of TiO2 significantly changed the crystal size, the surface morphology (surface area and pore size) of the TiO2 lattice, enhanced the catalysis activities, and significantly improved the POH. The SP-CPOH exemplified a promising energy efficiency when tested in a pure ED, IWW and MWW. The maximum POH of 5162 μmol/L corresponding to accumulated energy in the LPSPP of 123 kJ/L was achieved by Co–TiO2 composite with 5% Co at a pH of 8, with a photocatalyst loading (P–C–L) of 150 mg/L and the reaction time (τrxn) of 6 h. An alkaline pH and low organic matters (OMs) exhibited a positive effect on the POH, while a high electrolyte conductivity and acidic conditions resulted in a negative effect. The proposed SP-CPOH can be employed for the co-current treatment of wastewater and POH, which supports the environment and produces a valuable energy source.