Hydrogen Peroxide In Situ Production Using Water Electrolysis Powered by Photovoltaic Renewable Energy and Mg2+ Ions

In this paper, the novel electrochemical in situ synthesis process for H2O2, in which oxygen is in situ generated from water electrolysis powered by photovoltaic renewable energy and Mg2+ ions is added, is constructed by an ordinary Pt anode and a graphite or carbon felt cathode in a green, safe, low-cost, and high-yield way. The results show that the yields of hydrogen peroxide (YHP) for Mg(NO3)2 and MgSO4 are all higher than that for light MgO and are above 19.8 mg/L. The optimal Mg2+ concentration of 30 mg/L, pH of 1, current density of 30 mA/cm2, and cathodic immersion depth of 50 mm is determined, respectively. For solutions containing Mg2+, their YHPs are consistently higher than that of the Mg2+-free solution and properly adding Mg2+ into solutions can improve YHP. YHP for carbon felt cathodes is much higher than that for graphite plates, and the fluffy spatial structure of the cathode is beneficial to synthesis of H2O2. Additionally, YHP for pure oxygen blown into solution is the highest and 494.2 mg/L. Even if solar illumination intensity is very low, its YHP can reach to the same yield as high solar illumination intensity, too. In the meantime, the in situ synthesizing mechanism of H2O2 is suggested. Finally, their energy consumption and actual energy utilization efficiency are analyzed. The used method is feasible for the novel in situ synthesis of hydrogen peroxide.