TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The matrix is formed of a semiconductor or insulator material. The particles are formed of one or more of gold (Au), silver (Ag), aluminum (Al), copper (Cu), platinum (Pt), palladium (Pd), titanium (Ti), indium tin oxide, ruthenium (Ru), rhodium (Rh), tungsten (W), carbon (C) and graphene. The nanocomposite layer is porous. The matrix is formed of one or more of titanium oxide, silicon oxide, copper aluminum oxide (CuAlO2), Iron(III) oxide (Fe2O3), tin oxide (SnO2), zinc oxide (ZnO), graphene, silicon carbide (SiC), gallium nitride (GaN) and silver chloride (AgCl). The reflective layer comprises one or more of Au, Ag, Al, Cu, nickel (Ni), Pd, Ti and Pt. Spacer layer comprises a semiconductor or an insulator. The particles and matrix are formed of porous metal, carbon or graphene. Preferred Parameters: The spacer layer has a thickness from about 1 nanometers (nm) to 500 nm. The nanocomposite layer has a thickness from about 1 nm to 1 mu m. The photocatalyst is a colloid that is at least about 100 nm in diameter. The nanocomposite layer has a fill factor between 10% and 60%. Preferred Device: The photoelectrochemical system further comprises a power source that connects the first electrode to the second electrode. The reflector is the second electrode. It also comprises at least one reactant species in contact with the first electrode and/or second electrode. Preferred Process: Upon exposure of the first electrode to electromagnetic radiation, (i) the first electrode generates an oxidized product from the reactant species and (ii) the second electrode generates a reduction product from the reactant species. Upon exposure of the first electrode to electromagnetic radiation, (i) the first electrode generates a reduction product from the reactant species and (ii) the second electrode generates an oxidized product from the reactant species. The nanocomposite layer is nanopatterned. In catalyzing reaction, step (c) involves: (i) generating one or more reaction products from the at least one reactant species at the first electrode and the second electrode; (ii) generating an oxidized product from the reactant species at the first electrode and generating a reduction product from the reactant species at the second electrode; or (iii) generating an oxidized product from the reactant species at the second electrode and generating a reduction product from the reactant species at the first electrode.