The solar assisted splitting of water received great impetus as a legitimate research discipline as a result of the world energy crisis and the Arab oil embargo, and also from the initial reports of Fujishima, Honda, and their co-workers on the use of irradiated titanium dioxide. In the first part of the talk, the water splitting reaction and other reactions of technological interest will be discussed from the point of view of thermodynamics and kinetics. Approaches based on the use of electrodes and photoelectrodes as well as those based on the use of colloidal suspensions will be compared and contrasted.  Ideas on how we can learn from the intricate self-assembled architectures that Nature has evolved over millions of years, will be discussed with specific examples

The talk will then turn toward a discussion of the progress made with the generation of hydrogen as a renewable fuel and the notion of storing sunlight via chemical bonds (fuels). This will include work in the author’s laboratory on the use of carbon and oxide semiconductor nanocomposites for driving catalytic processes of interest both in the dark and under irradiation of the oxide semiconductor component. Incorporation of bioinspired components such as flavins in these assemblies will be described. The reactions of interest here include dioxygen reduction and the reduction of carbon dioxide to fuels such as methanol. The role of the nanocomposite components and their complementary functionality within the material architecture will be discussed within the context of systems that Nature has evolved. Other complex oxides and their preparation from solution combustion synthesis will also be elaborated.

Finally the talk will turn toward the very recent work in the author’s laboratory on the solar photoelectrosynthesis of methanol from CO₂.  This process was driven on hybrid CuO/Cu₂O semiconductor nanorod arrays for the first time at potentials ~800 mV below the thermodynamic threshold value and at Faradaic efficiencies of ~95%.  Subsequent studies have developed flow reactors as well as new electrode materials. 

The presently unknown aspects of this process as well as its "dark" process counterpart, especially details on how atomic hydrogen adds to the CO₂ molecule along with scission of the carbon-oxygen double bond and even formation of carbon-carbon double bonds (in the formation of ethylene), will be discussed in the light of the new role that renewable hydrogen can play in the future.