| Electrochemical advanced oxidation processes（EAOPs）stand out as an efficient treatment technology for contaminants degradation,owing to its attractive advantages such as environmental friendly,high treatment performance and easily operation.The anode is the core component of EAOPs.Compared with other electrodes,dimensionally stable anode（DSA）have become one of the best choices in the field of electrochemical water treatment due to the desirable features such as high stability of the active coating,good electrochemical catalytic performance and low cost.However,DSA anode also faces a series of challenges,such as the intensive use of chemical reagents in the pretreatment of Ti substrate and the improvement of electrode service life.Therefore,it is of great significance to develop an environmentally friendly strategy for Ti substrate pretreatment and enhance its stability for the practical industrial application of DSA electrode.In view of this,a simple and green strategy was developed to thermally pretreat the Ti substrate in the atmosphere of H2 and N2（molar ratio 1:5）without chemicals consumption and wastewater discharge.It was found that both Vo·and Ti3+were created in Ti O2 after thermal reduction at 750°C.This rendered Ti/reduced Ti O2/Ru O2-Ir O2-Sn O2-Sb2O5 anode with better stability and higher electrocatalytic activity.The accelerated lifetime for Ti/reduced Ti O2/Ru O2-Ir O2-Sn O2-Sb2O5 electrode was 65 h with the optimum catalyst loading amount(2.6±0.05 mg cm-2),while it was only 50 h for traditional Ti/Ru O2-Ir O2-Sn O2-Sb2O5 electrode.As compared with the counterparts,Ti/reduced Ti O2/Ru O2-Ir O2-Sn O2-Sb2O5 with higher oxygen evolution potential（1.42V/SCE）and lower chlorine evolution potential（1.12 V/SCE）,suggesting that it exhibited higher electrocatalytic activity.The main cause for the deactivation of the electrode anode was the gradual dissolution of Ru O2,Ir O2,Sn O2 and Sb2O5 in the catalyst layer,which resulted in the formation of the oxidized Ti O2.Ibuprofen was used as a model pollutant to evaluate the degradation ability of the different electrodes.The results show that the removal efficiency of ibuprofen by Ti/Ru O2-Ir O2-Sn O2-Sb2O5 and Ti/reduced Ti O2/Ru O2-Ir O2-Sn O2-Sb2O5 electrodes reached 84%and 96%respectively at 120 min when the initial p H of the solution is 7.0 and the current density is 20 m A cm-2.Highly ordered TiO2 nanotube arrays（Ti O2-NTs）can be easily grown in situ on Ti substrate by anodization of the Ti substrate.In this paper,the Ti O2-NTs were heat-treated at 750°C in the atmosphere of H2 and N2（molar ratio 1:5）.It was found that the Ti O2-RNTs had larger surface area,which provided more anchor sites for the catalyst.The Ru O2-Ir O2-Sn O2-Sb2O5 were coated on Ti O2-NTs and Ti O2-RNTs by sol-gel method to produce Ti/Ti O2-NTs/Ru O2-Ir O2-Sn O2-Sb2O5 and Ti/Ti O2-RNTs/Ru O2-Ir O2-Sn O2-Sb2O5 electrodes,respectively.And the properties of these electrodes were compared in terms of surface morphology,crystal structure,electrochemical properties,stability and organic pollutant degradation properties.Ti/Ti O2-RNTs/Ru O2-Ir O2-Sn O2-Sb2O5 electrodes have compact and smooth surfaces.Furthermore,Ti/Ti O2-RNTs/Ru O2-Ir O2-Sn O2-Sb2O5 electrode showed better stability under the same experimental conditions.The accelerated lifetime for Ti/Ti O2-RNTs/Ru O2-Ir O2-Sn O2-Sb2O5 electrode was 77.8 h,while it was only 68 h for traditional Ti/Ti O2-NTs/Ru O2-Ir O2-Sn O2-Sb2O5 electrode.As compared with the counterparts,Ti/Ti O2-NTs/Ru O2-Ir O2-Sn O2-Sb2O5 with higher oxygen evolution potential（1.75 V/SCE）and lower electron transfer resistance（0.54Ω）,suggesting that it exhibited higher electro-catalytic activity.Carbamazepine was used as a model pollutant to evaluate the degradation ability of the different electrodes.The results show that the COD removal efficiency of carbamazepine by Ti/Ti O2-NTs/Ru O2-Ir O2-Sn O2-Sb2O5 and Ti/Ti O2-RNTs/Ru O2-Ir O2-Sn O2-Sb2O5 electrodes reached 52%and 63%respectively at 120 min when the initial p H of the solution is 7.0 and the current density is 20 m A cm-2.Generally,the simple and green strategy of Ti substrate modification was adopted in this paper.The introduction of Ti O2 and Ti O2-RNTs interlayer improved the electrocatalytic performance and stability of DSA electrode.Therefore,the research of this paper is of great significance to the practical industrial application of DSA electrode. |
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