A new class of photo-catalytic materials and a novel principle for efficient water splitting under infrared and visible light - MgB2 as unexpected example

摘要

Water splitting is unanimously recognized as environment friendly,potentially low cost and renewable energy solution based on the future hydrogeneconomy. Especially appealing is photo-catalytic water splitting whereby asuitably chosen catalyst dramatically improves efficiency of the hydrogenproduction driven by direct sunlight and allows it to happen even at zerodriving potential. Here, we suggest a new class of stable photo-catalysts andthe corresponding principle for catalytic water splitting in which infrared andvisible light play the main role in producing the photocurrent and hydrogen.The new class of catalysts based on ionic binary metals with layeredgraphite-like structures which effectively absorb visible and infrared lightfacilitating the reaction of water splitting, suppress the inverse reaction ofion recombination by separating ions due to internal electric fields existingnear alternating layers, provide the sites for ion trapping of both polarities,and finally deliver the electrons and holes required to generate hydrogen andoxygen gases. As an example, we demonstrate conversion efficiency of 27 percentat bias voltage bias 0.5 V for magnesium di-boride working as a catalyst forphoto-induced water splitting. We discuss its advantages over some existingmaterials and propose the underlying mechanism of photo-catalytic watersplitting by binary layered metals.