Investigation of Photoelectrocatalytic and Magnetic Properties of SrYbRuTaO ( = 0, 0.25, 0.5, 0.75, and 1).

We report the effect of substitution of Ru by Ta in SrYbRuO on its magnetic and photoelectrocatalytic properties. The powder X-ray diffraction data, was satisfactorily refined in the monoclinic space group, 2/. The DC magnetization studies indicated that SrYbRuO shows antiferromagnetic interaction through Yb-O-Ru orbital ordering, with the highest Weiss temperature, among SrYbRuTaO ( = 0, 0.25, 0.5, and 0.75) which have values of -148, -125, -118, and -102 K, respectively. The difference in observed and theoretical magnetic moments was found to increase as increases. It was also observed that with the increase of Ta concentration in SrYbRuTaO, the band gap increased almost linearly, from 1.78(1) eV ( = 0) to 2.08(1) ( = 0.75), and thereafter a sharp increase 2.65(1) eV ( = 1) was observed, with the lowering of energy level of valence band, along with disruption in orbital ordering as increases. The photoelectrocatalytic oxygen evolution reaction (OER) studies carried out on the series yield a maximum photocurrent density of 17 μA/cm and photoresponse current of 5.5 μA/cm at 0.8 V at an onset potential at 0.29 V vs Ag/AgCl for SrYbRuO. The XPS analysis showed Ta and Ru to be in +5/+4 oxidation states, with the highest concentration of Ru ion observed for SrYbRuO. The presence of oxygen vacancies was confirmed by XPS as well as EPR studies.