Cobalt oxyhydroxide co-catalyst loaded onto Al:SrTiO3 surface to boost photocatalytic performance

In photocatalysis, a common challenge is the rapid recombination of photogenerated electrons and holes, coupled with low surface reaction efficiency in aqueous environments. This study addresses these issues by improving the photocatalytic performance of Al3+-doped SrTiO3 perovskite through the strategic loading of CoOOH onto its surface. We successfully demonstrated that the combined approach of Al3+ doping and CoOOH co-catalyst functionalization significantly enhances the photocatalytic performance of SrTiO3. The Al3%:SrTiO3 was functionalized with CoOOH using a two-step process. This process involved the oxidation of Co2+ ions to Co3+ ions, followed by the precipitation of cobalt oxyhydroxide (CoOOH) onto the surface of Al3%:SrTiO3, resulting in the formation of an Al3%:SrTiO3@CoOOH composite heterostructure. The UV-Vis data shows an enhanced light absorption capabilities into the visible spectrum with a direct band gap of 1.73 eV in contrast to 3.24 eV for the pristine perovskite. XPS analysis confirms the surface functionalization with CoOOH co-catalyst and the determined 1:1 Sr:Ti stoichiometry, the reduced state of Al, and the absence of oxygen vacancies were identified as beneficial properties for photocatalytic applications, as shown in DFT calculations. The oxacillin photodegradation was tested at three different concentrations of Al3%:SrTiO3@CoOOH photocatalyst (0.25 g/L; 0.5 g/L and 1 g/L) and we observed that the removal efficiency significantly varies from 99 % for 1 g/L Al3%: SrTiO3@CoOOH to 78 % and 44 % for 0.5 g/L and, respectively 0.25 g/L. Additionally, under visible light irradiation, the Al3%:SrTiO3@CoOOH composite achieved an exceptional degradation rate of the (3-lactam antibiotic oxacillin of up to 99 %, with holes identified as key players in the photocatalytic process. This study highlights that effective surface modification using a well-chosen co-catalyst can substantially boost the photocatalytic efficiency of semiconductor-based materials, offering a promising strategy for developing advanced photocatalysts for environmental remediation applications.