Abstract
The high activation energy needed for C–H bond activation leads to the requirement
for harsh reaction conditions, specially designed catalysts, additives, and terminal
oxidants. Tremendous progress has been achieved in C–H bond activation using thermocatalysis,
photoredox, electrocatalysis, and electrophotocatalysis methods. Recently, photoelectrochemistry
using semiconductor photoanodes has been explored for C–H bond activation, and the
approach has certain advantages and challenges. The use of both light and applied
potential makes C–H bond activation facile compared to the electrochemical or photoredox
reactions. Further, high atom economy, low side product and waste formation, mild
reaction conditions, and high energy efficiency associated with photoelectrochemistry
make it more convenient than the other processes. However, the design of effective
photoanodes using a suitable choice of semiconductor and cocatalyst is crucial for
improving the charge-transfer dynamics, reaction rates, and selectivity for the desired
products. Although the field is relatively new, a significant number of studies have
demonstrated its versatility and robustness for different types of C–H bond activation.
Herein, we describe the scope of photoelectrochemistry for C–H bond activation and
discuss its future and potential for large-scale organic synthesis.
1 Introduction
2 Types of C–H Activation
3 Importance of Photoelectrochemical Approaches
4 Improvement of the Activity
5 Control over the Selectivity
6 Photoanode Design
7 The Effect of Cocatalysts
8 The Effect of Charge Collectors
9 The Effect of Redox Mediators
10 Conclusions and Perspectives
Key words
C–H bond activation - hydrogen atom transfer - photoelectrochemistry - photoanode
design - selectivity
