Photoelectrocatalytic Performance Of Er³⁺:YAlO₃/RGO/TiO₂ Electrode Under Visible Light Irradiation

In the industrial wastewater,the increased amount and varieties of the poisonous and harmful refractory organic compounds have the risk of making people getting cancer and distortion.It threatens the human health.So it’s crucial to take effective measures to treat industrial organic wastewater.However,physical method cannot remove pollutants in the true sense,biological method demanded high biodegradability,while photoelectrocatalysis method was paid much attention in the environment field due to the mild reaction conditions,low cost and no secondary pollution.The research and development of electrode material is the key factor in the use of photoelectrocatalysis method.In the research,the up-convertion agent-Er³⁺:YAlO₃ and reduced graphene oxide（RGO）with excellent electron transmission characteristic and great adsorption performance were used to co-couple with TiO₂ to prepare Er³⁺:YAlO₃/RGO/TiO₂（ERT）powder photocatalyst,take optimization with response surface model（RSM）,then the ERT electrode was prepared by loading the ERT powder catalyst on the FTO conductive glass to set up the photoelectrocatalytic（PEC）system.Meanwhile,the corresponding X-ray diffraction spectrum（XRD）,X-ray photoelectron spectroscopy（XPS）,UV-visible diffuse reflection spectroscopy（DRS）,photoluminescence（PL）and scanning electron microscope（SEM）measures were applied to characterize the electrode,combined with photocurrent response test,electrochemical impedance spectrum（EIS）test,PEC performance test to theexplore different reaction conditions on the photoelectric catalysis efficiency.The experimental results showed that the optimal preparation conditions by optimization were the hydrothermal temperature-180°C,hydrothermal time-20 h,GO ratio-26%.And ERT could effectively accelerate the electron transfer and conduction,restraining the recombination of photo-generated electrons and hole pairs as well as improved the response to the visible light,improved the utilization rate of light energy and emitted ultraviolet light to excite TiO₂ to produce photo-induced holes with high oxidation potential energy to improve the efficiency of the adsorption and catalytic degradation to pollutants.Besides,the PEC by the ERT electrode showed the highest MB removal with the corresponding first order reaction kinetics constants of 0.0307 min^-1 compared with those by the electrodes coupled with RGO-0.0228 min^-1 or Er³⁺:YAlO₃-0.0148 min^-1 alone.In addition,the kinetic rate constant of the PEC process by the ERT electrode was higher than the solely process of the photocatalysis（PC）-0.0110min^-1 and electrocatalysis（EC）-0.0063 min^-1 processes as well as higher than the sum of those of PC and EC,namely0.0173 min^-1,which indicated that there existed the synthetic effect between PC and EC.GO,Er³⁺:YAlO₃ and the external bias voltage promoted catalytic reaction together.The optimal conditions for PEC process by the ERT electrode under visible light irradiation were an external bias voltage of 1.0 V,0.1 mol/L Na₂SO₄ and pH=10,respectively.The research provided new ideas for efficient treatment of dye wastewater.