| Hydrogen is generally considered to be an ideal energy carrier combines several attractive features as abundant, environmentally benign and renewable for energy utilization. With the improvements in performance of photovoltaic(PV) cell and sharp increase in costs of fossil fuels, hydrogen generation using solar energy water splitting, features the most promising alternative for the fuel of the future, will result in a permanent energy system.The aim of the paper was the attempt to present an efficient coupling solar-hydrogen system by using a combination of separate PV modules and water electrolytic systems operating the electrolysis cells efficiently at the maximum power point(MPP) of PV modules without maximum power point tracker(MPPT). Based on an integrated and self-coupled model and its theoretical analysis, the efficient and stable noble metal Titanium based oxides electrode for light splitting water were fabricated by molecular design, rare earth doping techniques. By using the photocell unit and electrolytic unit, four systems of solar energy to generate hydrogen will be fabricated and studied by matching and coupling of energy, potential and efficiency.As we all know, the overpotential of oxygen evolution is more difficult to reduce than that of hydrogen evolution in water electrolysis. A lot of rare earth doping titanium-based anodes were prepared by sol-gel process. The surface and morphology of the coating anodes were characterized by SEM, EDS and XRD. Electrocatalytic activity on these electrodes in 1.0mol?dm-3 KOH solution were studied recording open-circuit potential (Eoc), cyclic voltammetry (CV), voltammetric charge (q*) and polarisation curve. The results showed that the appropriate content of rare earth element could reduce the grain size and increase active surface area. Mixed oxide electrodes doping with cerium, lanthanum and neodymium, Ru0.3Co0.7Ce0.3, Ru0.3Co0.7La0.1, Ru0.3Co0.7Nd0.05 had the greatest voltammetric charge and decrease the standard electrochemical energy of activation for oxygen evolution reaction (OER) with 27.18%, 25.00%, 25.06% compared to Ru0.3Co0.7 electrode for OER respectively. Ru0.5Sn0.2Ce0.3 showed the best electrocatalytic performance for OER among Ru0.5SnxCe0.5-x electrodes. As a result, these electrodes have found to be able to reduce the overpotential of oxygen evolution efficiently in alkaline electrolysis. Based on the two most efficient anodes as Ru0.5Sn0.2Ce0.3 and Ru0.3Co0.7Ce0.3, the electrolytic units of the coupling solar hydrogen generation system were fabricated. The overarching parameter is the operating cell voltage, which determines the energy consumption and electricity efficiency directly. A higher voltage at the same current to produce equivalent hydrogen means inefficiency. Focused on high efficiency of solar hydrogen conversion and performance of different solar cell materials, four PV modules including c-Si serially connected, poly-Si serially connected, AlGaAs/Si and GaInP2/GaAs/Ge were built. The results show that the PV modules can provide enough voltage to drive the energetics of water cleavage.On the basis of the above-mentioned model, theoretical analysis, the performance PV module and electrolytic unit, four direct coupling of solar-hydrogen systems including [∑(c-Si PV cells serially)/1(RuCoCe/KOH/Pt)],[∑(serially poly-Si PV cells)/∑(RuCoCe/KOH/Pt)],[1(AlGaAs/Si)/1(RuSnCe/KOH/Pt)] and [1(GaInP2/GaAs/Ge)/∑(RuSnCe/KOH/Pt)] were studied. The results show the I-V characteristics of the PV modules and electrolytic units are crossing each other at the operating point of the coupling system. With the increase of the temperature, the operating points of the four coupling systems move closer to the Maximum Power Point Tracking (MPPT) of the corresponding PV modules. An efficiency of over 20% was determined for the solar to hydrogen production by using [1(GaInP2/GaAs/Ge)/∑(RuSnCe/KOH/Pt)] system under the light intensity of 100 mW cm-2.
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