A chemically passivated photoelectrode, having a conductive substrate, a layer of conductive oxide, preferably zinc oxide (ZnO), over the conductive substrate, and an ultrathin layer of a chemically inert semiconductor material coating the conductive oxide layer, is disclosed. The ultrathin layer of chemically inert semiconductor material, which may be less than 5 nm thick, increases the efficiency of water splitting through passivation of surface charge traps and chemical stability in harsh environments, as opposed to being photoactive. A method of manufacture and a solar cell having the photoelectrode are also disclosed.
STATEMENT OF GOVERNMENT LICENSE RIGHTS
 The present invention was made with government support under contract number DE-AC02-98CH10886 awarded by the U.S. Department of Energy. The United States government has certain rights in the invention.