Sustainable Nanoplasmon-Enhanced Photoredox Reactions: Synthesis, Characterization, and Applications

Plasmonic materials with their unique properties, such as light-excitable resonant oscillation of conduction electrons, strong local electric field, and energetic hot charges (electrons/holes) etc., have overcome the limitations of traditional photoredox catalysts. They are especially important due to their superior light focusing ability, from free-space wavelengths to the sub-wavelength range. Although noble metal plasmonic enhancement has been recognized as one of the most important strategies in photocatalysis, the high cost and limited spectral range absorption of noble metals remain the biggest challenges for their practical application, which has led to a gradual shift in the focus on the abundant and less expensive non-noble metal plasmonics. Recently, various non-noble plasmonic materials such as non-noble metals (Cu, Al, Ni and Bi), metal oxides and chalcogenides (WO_3-x, MoO_3-x, NiO, MNbO₃, where M = Ca, Sr or Ba; Fe₂O₃, SrTiO₃, In₂O₃, Cu_2-xS and Bi₂Se₃), nitrides (TiN, ZrN, HfN and WN) have emerged as efficient photocatalysts. Herein, the door to the relatively new and exciting world of noble metal-free plasmonic materials and their promising applicability in solar-energy driven photo-redox catalysis such as water splitting, CO₂ reduction, nitrogen reduction, organic transformations and environment remediation is opened. Their synthesis methods and a plethora of characterization techniques are also systematically exhibited.