As a fundamental step towards a clean, renewable source of H2, a novel physical chemical process within molten NaOH in which an external single, small bad gap photosentizer, such as Si, can drive the energetics of water cleavage is demonstrated, and is accomplished by tuning (decreasing) the water splitting electrochemical potential, EH2O, rather than tuning the photosensitizer band gap; this diminished potential is due to (i) a thermodynamic temperature induced decrease of EH2O with increasing temperature, and (ii) a partial recombination of the cleavage products.