Strategies for optimizing sunlight conversion in semiconductor photocatalysts: A review of experimental and theoretical insights

Abstract

Photocatalysis via sunlight conversion holds an enormous potential for tackling universal energy demand and environmental pollution. However, the inadequate conversion of irradiated sunlight severely limits the efficiency of semiconductor photocatalysts, where usually responsible factors, including light absorption, separation of photo-generated electron-hole pairs, and interfacial charge kinetics do not contribute efficiently. Herein, the recent advances in the most versatile and emerging design strategies as viable routes to overcome inadequate sunlight conversion efficiency in photocatalytic applications are discussed. This review first introduces various design strategies to expand the spectral response of photocatalysts, which extend light harvesting toward a large fraction of the solar spectrum, and dictate how photons' high potential is utilized to generate electron-hole pairs. We then discuss efficient strategies to obtain high separation of electron-hole pairs, and—when compared to high recombination loss of charge carriers—increased lifetime plays a pivotal role in promoting sunlight conversion. Furthermore, to elucidate the relationship between charge kinetics and sunlight conversion, the next section includes an in-depth discussion of various strategies, which clarify that charge migration and subsequent utilization can be enhanced by manipulating charge kinetics. Novel insights into the future views, which illustrate how high-performance photocatalysts require enhanced sunlight conversion, are also discussed. This review offers guidance toward emerging photocatalytic strategies for improved sunlight conversion.