Disclosed is a water-splitting photocatalyst, and methods for its use, that includes a photoactive semi-conductive layer, an up-converting material capable of converting infrared (IR) light to visible light and/or ultraviolet (UV) light, and a metal or metal alloy material having surface plasmon resonance properties in response to IR light and/or visible light, wherein the photoactive semi-conductive layer encompasses at least a portion of the up-converting material and the metal or metal alloy material.