Recent Advances in Noncontact External-Field-Assisted Photocatalysis: From Fundamentals to Applications

Abstract

The effective separation of photogenerated carriers plays a vital role in photocatalytic reactions. In addition to the intrinsic driving force of photocatalysis, an external field generating an enhancement effect can provide extra energy to the photocatalytic system, acting as an additional impetus to separate photogenerated charges and thus improving the overall catalytic efficiency. Under the favorable noncontact conditions, exploring the effect of the external field, different from pure photocatalysis or photoelectrocatalysis, could widen the applications of photocatalysis technology. In this review, four typical noncontact external fields (i.e., thermal, magnetic, microwave, and ultrasonic fields) and their coupling effects on photocatalysis are summarized. Specifically, the review focuses on the mechanism and characteristics of each external field’s synergistic effect and their coupling effects on the performance of the catalytic system. The charge separation driving forces provided by the noncontact external field and the traditional one are distinguished and defined for the first time. The challenges and future prospects of noncontact external-field-driven photocatalysis are discussed. We hope that this review will provide a reference for the research and development of external-field-assisted photocatalysis and give insights for the in-depth study of external-field-coupling-enhanced photocatalysis toward improvement of the catalytic efficiency.

NiAl‐LDH In‐Situ Derived Ni2P and ZnCdS Nanoparticles Ingeniously Constructed S‐Scheme Heterojunction for Photocatalytic Hydrogen Evolution

“…The combination of two or more different semiconductors, due to their different energy band structure and potential difference, will cause the separation of e À -h + to accelerate. [20][21][22] The construction of heterojunction compounds can significantly improve the hydrogen evolution efficiency of the catalyst. [23][24][25] Layered double hydroxides (LDH), also known as a hydrotalcite-like compounds, consists of a layer of positively charged metal hydroxide and exchangeable anions ([M 2 + 1-x M 3 + x (OH) 2 ] (A n À ) x/n •mH 2 O).…”

Photocatalytic nitrogen reduction to ammonia: Insights into the role of defect engineering in photocatalysts

“…Aside from the inherent driving force of photocatalysis, introduction of an external field can provide additional energy to promote light generation and charge separation and migration, thereby improving the overall catalytic efficiency [322]. This emerging scheme has been recently combined with defect engineering in photocatalytic N2 reduction.…”

“…To synergistically promote N2 photocatalysis, integration of multiple design strategies (e.g., defect engineering and other modification strategies such as creation of Z-scheme heterostructures to separate ammonia production and water oxidation sites in space) is preferred. Additionally, combination of defect engineering and external fields (e.g., microwaves, mechanical stress, temperature gradient, electric field, magnetic field, and coupled fields) is another promising strategy to further boost photocatalytic N2 reduction reactions [322].…”

Polydopamine and Nafion bi‐layer passivation modified CdS photoanode for photoelectrochemical hydrogen evolution

“…Generally, longer charge carrier lifetime usually represent a higher probability of their participation in catalytic reactions and therefore imply better photoelectricity catalytic activity. 48,49 Therefore, to obtain quantitative knowledge of the photogenerated charge carrier lifetime in all samples, the TRPL attenuation curve is fitted with the following double exponential function to obtain the photoluminescence lifetime of all photoelectrodes:…”