Photoelectrochemical cells for solar hydrogen production: Challenges and opportunities

As the Holy Grail to a carbon-free hydrogen economy, photoelectrochemical (PEC) water splitting offers a promising path for sustainable production of hydrogen fuel from solar energy. Even though much progress has been made over the past decade, the effectiveness and robustness of PEC cells are still far from a mature phase that would allow for widespread deployment. This perspective discusses the key challenges facing the current level of PEC development and proposes experimental approaches and strategies that can be adopted to address the issues. Focuses are mainly placed on the employment of in situ and operando spectroscopic measurements, the introduction of alternative, high value-added oxidation reactions, and the creation of near infrared-responsive photoelectrodes. A brief outlook that may assist the future advancement of PEC technology is also presented.