Interfacial Charge Transfer in Photoelectrochemical Processes

Abstract

Solar light harvesting and conversion to useful energy are the most important tasks for overcoming the world energy crisis. The design of advanced materials for solar light conversion requires focused research to obtain efficient photocatalytic systems. Photogenerated charge carrier separation is a crucial prerequisite in applications such as photo‐electrochemical water splitting, photovoltaics, and photocatalytic dye degradation. Interfacial charge‐transfer (IFCT) plays a significant role in electron–hole separation considering the energy barriers of the energy levels at semiconductor–semiconductor, semiconductor–metal, semiconductor–molecule, and semiconductor–electrolyte interfaces. Both electron and hole transport across the interface via IFCT, with comparable rates, are important for maintaining enhanced photocatalytic efficiency and stability of the catalysts. The key focus of this article is to understand the charge transfer processes at the interface and the relationship between photogenerated charge separation and photocatalytic activity. The interfacial charge transfer in different interfaces is discussed, along with the fundamentals of IFCT in photo‐electrochemical processes; semiconductor heterojunctions with materials having proper band alignment and offer new ways to design multifunctional photocatalysts are also disucssed. The charge transfer process from semiconductor to catalyst molecules and dye molecules to semiconductor is explained in detail.

Integrated Heterostructure of PDA/Bi‐AgIn5S8/TiO2 for Photoelectrochemical Hydrogen Production: Understanding the Synergistic Effect of Multilayer Structure

“…Titanium dioxide (TiO 2 ) has emerged as one of the most attracting semiconductors to realize the green hydrogen production through photoelectrochemical (PEC) water splitting . The excellent stability and high abundance of TiO 2 make it very attractive in PEC systems.…”

Inside‐and‐Out Semiconductor Engineering for CO2 Photoreduction: From Recent Advances to New Trends

“…The charge separation and transport process take place within 10 −6 s, and the surface reaction is a process of 10 −4 s. In contrast, the recombination of electrons and holes occurs from 10 −12 to 10 −3 s, and particularly the recombination in the bulk phase of photocatalysts (approximately several picoseconds) is much faster than other processes and it also tends to occur through the entire photocatalytic process. [ 40,123–125 ]…”

Strategies for Plasmonic Hot‐Electron‐Driven Photoelectrochemical Water Splitting

“…During photoelectrocatalysis, a space charge depletion layer occurs at the semiconductor‐liquid electrolyte interface (also known solid–liquid junction), which stimulates the upward band bending in a photoanode and downward band bending in a photocathode . This potential profile, which depends on the relative alignment of the semiconductor work function and the reaction potential, enables the efficient separation of photoinduced charges and prevents the recombination of e − ‐h + pairs .…”