Piezotronics in Photo-Electrochemistry.

Photo-electrochemistry is the major trajectory for directly transforming solar energy into chemical compounds. The performance of a photo-electrochemical (PEC) system is directly related to the interfacial electrical band energy landscape. Recently, piezotronics has stood out as a promising strategy for tuning interfacial energetics. It applies intrinsic or deformation-induced ionic displacements (ferroelectric and piezoelectric polarizations) to engineer the interfacial charge distribution, and thereby the band structures of PEC electrodes. Here, contemporary research efforts of coupling piezotronics with photo-electrochemisty are reviewed. Quantitative band diagrams of a polarization-tuned semiconductor-electrolyte junction are first introduced, with an emphasis on the impact of interface chemistry. Experimental advances of employing piezoelectric and ferroelectric polarizations to enhance the charge separation and transportation, and surface kinetics of PEC water splitting are discussed. Finally, critical challenges of applying piezotronics in PEC systems and promising solutions are presented.