Study on the Photoelectrocatalytic Performance of Ti/Ti-W-O Coating Photoelectrodes Prepared by the Microarc Oxidation Method.

Abstract

Photoinduced cathodic protection is an environmentally friendly, economical, and sustainable technology that has been widely used in the corrosion protection of alloy materials. In this study, the corrosion-resistant Ti/Ti-W-O ceramic coatings are prepared by changing the concentration of additives, microarc oxidation voltage, pulse frequency, and time using titanium alloy (TC4) as the substrate and sodium tungstate (Na₂WO₄) as the main additive via the microarc oxidation (MAO) method. The optimum parameters were determined as follows: concentration of added salt (Na₂WO₄): 0.05 mol/L; reaction conditions: anode voltage 300 V, cathode voltage 30 V, duty cycle 1:1 (50%), frequency 800 Hz, and reaction time 5 min. They were evaluated from two perspectives: photocathodic protection and photocatalysis, respectively. The test results show that the composite coatings have more negative conduction band potentials, narrower band gaps, higher photocurrent densities, and smaller impedance arc radii under the same conditions as those analyzed in the electrochemical workstation test. In addition, the optimized Ti/Ti-W-O composite photoelectrode coupled with 304 stainless steel showed the largest negative shift in corrosion potential (447 mV vs) and improved degradation efficiency of the dyeing wastewater (improved by ∼20%). The above results demonstrate that the composite electrodes in this study exhibit good performance in photocathodic protection and photovoltaic synergy.