Harvesting broadband absorption of the solar spectrum for enhanced photocatalytic H2 generation

Abstract

Absorption of the solar spectrum in the visible and near infrared region is highly desirable to improve photocatalytic H₂ generation. Traditionally, this can be fulfilled by designing photocatalyst materials with narrower band gaps, or with upconversion capabilities. However, such materials often pose challenges such as in synthesis, structural defects, and stability which may lead to adverse photocatalytic performance. This paper focuses on broadband utilization of the solar spectrum for enhanced photocatalysis solar H₂ production where the spectrum not utilized by the photocatalysts is absorbed and converted to heat energy. This approach delves into harvesting the broadband spectrum for synergistic photocatalysis and thermal heat generation, with minimal photocatalyst material manipulation. The profound impact of temperature on photocatalysis was manifested in a drastic increase of H₂ production by a maximum of 40-fold. The apparent quantum yield was also calculated to reach 66.9% using an ultraviolet LED light source. Outdoor testing verifies the potential of broad spectrum operation under natural sunlight as well as the convenience and simplicity of various reactor designs for practical photocatalysis applications.