Surface and bulk modification for advanced electrode design in photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting provides a prominent strategy for harnessing solar energy in the production of sustainable hydrogen fuel from water. Over the past few decades, extensive efforts have been devoted to develop advanced electrodes for efficient PEC water splitting. This review presents the recent progress in the development of efficient photoanodes through two major approaches: surface modification, including co-catalyst-loading, passivation, and defect engineering; and bulk modification, including hybridization, dopant engineering, and structural control. By virtue of bulk and surface modification a considerable improvement in PEC activity has been obtained so far. Photocurrent response of various anodes observed in the range of 0.063 mA cm⁻² – 8.5 mA cm⁻² (as listed in Table 1) require further improvement to upgrade the overall performance efficiency of PEC cells. This review also provides a systematic overview of the fundamentals of PEC water splitting, as well as the key challenges and notable achievements made so far in terms of electrode design and material modification. Finally, future research perspectives that will further advance this field are discussed. The contribution of this paper is to provide fundamental information about bulk and surface modifications, which will aid in the design of advanced electrodes for high-performance PEC cells.