p-Cu_2O-ZnO heterojunction applied to visible light Orange II degradation

摘要

The p-Cu_2O-ZnO system is studied for its potential use as a photoactive heterojunction able to highly perform under visible light. The main application deals with the degradation of organic dyes such as Orange II and the effects of CU_2O amount, Orange II concentration and light intensity are investigated. Results show that the kinetics of degradation follows a pseudo-first order and the optimum sensitization effect is obtained using a 70% concentration of Gu_2O. The degradation rate reaches its maximum (R_(initial) = 22.45 × 10~(-2) mg l~(-1) min~(-1)) at 15 mg l~(-1) of Orange II. The effect of the irradiation intensity is also investigated taking the electrical energy consumption per order of magnitude (EE/O) as a figure of merit. The highest efficiency is obtained at an irradiation intensity of ～122 × 10~(-5) kW with k_(OBS) = 14.97 × 10~(-3) min~(-1) and EE/O, which corresponds to 12.54 kW h m~(-3) of energy consumption. This heterojunction allows a ～25% saving of electrical energy in comparison to the p-Cu_2O-TiO_2 system, demonstrating the important role of the collector.