Semiconducting photocatalysis for solar hydrogen conversion

Mounting global energy consumption and aggravated environmental pollution urgently require us to develop carbon-neutral renewable energy on a scale comparable to the energy supplied from the conventional fossil fuels. Solar energy is the largest exploitable renewable resource; however, its intermittency of insolation and geographical maldistribution bring us another problem: How to efficiently collect and store solar energy? On this front, semiconductor-based photocatalytic water splitting to store solar-converted energy in the form of chemical bonds, namely, H₂ and O₂, is an especially intriguing approach. To date, the field of semiconducting photocatalysis for solar hydrogen generation from water has progressed significantly with knowledge and theories learned and proposed, myriad of new photocatalysts discovered and improved, and lots of synthesis and modification strategies developed. This chapter herein introduces the basic knowledge and main topics with a brief review on the representative works in this field in past years. In addition, the key factors dominating the efficiency of solar water splitting (i.e., optical absorption, charge separation and migration and surface catalytic kinetics) are highlighted and some commonly used and effective strategies for developing efficient and stable semiconductor photocatalysts (e.g., band structure engineering, heterojunction construction, surface modification, etc.) are summarized and discussed.