On the Similarity and Dissimilarity between Photocatalytic Water Splitting and Photocatalytic Degradation of Pollutants

Abstract

The last four decades have shown a remarkable increase in scientific interest in photocatalysis as a tool for tackling the world's energy and waste problems. The apparent similarity between photocatalytic water splitting and photocatalytic degradation of pollutants, which have been studied so far by two different scientific communities, raises the question regarding the extent to which one may utilize knowledge obtained in one field for the benefit of the other. This review examines the common features and differences between the two areas. The main similarities stem from the common dependence on the absorption of photons and on subsequent charge-carrier dynamics. The main dissimilarities are linked to thermodynamics, the type of reactants and end products, and to the role of adsorption and desorption. At present the fundamental differences between storing energy and using it to solve environmental issues affect practical solutions. Yet, easy transfer of knowledge, research resources, and personnel between the two is not only possible but should be encouraged.

Treatment of Organic Pollutants Using a Solar Energy Driven Photo‐Oxidation Device

“…In particular, photo‐electrochemical oxidation is able to remove toxic organics, ecologically hazardous cyanides and other residual compounds even at low concentrations, being therefore an ideal candidate for advanced water purification . This method uses the light absorbed in a semiconductor to degrade the pollutants into less complex compounds that can be easier to remove by a post‐treatment step.…”

Facet‐Engineered Surface and Interface Design of Photocatalytic Materials

“…[17,32] This feature manifests that the species adsorption and activation plays a more prominent role in dye degradation, while the water splitting raises higher demand for band structures. [85] In many cases, the activity of a facet is influenced by a mix of different catalytic mechanisms. For instance, both internal electronic field and species adsorption contributed to the superior photocatalytic activity of BiOBr{001} to BiOBr{010} in degradation of 2,4-dichlorophenol and inactivation of Escherichia coli; [74,75] CeO 2 {100} and CeO 2 {110} offered suitable band structure for generating more energetic holes and more O vacancies for catalytic active sites, respectively, which caused to exhibit different photoreactivitiy in photocatalytic oxidation of volatile organic compound and O 2 evolution reaction.…”

Facet Effects of Ag3PO4 on Charge‐Carrier Dynamics: Trade‐Off Between Photocatalytic Activity and Charge‐Carrier Lifetime

“…OH and O 2 (Figure d and e) can presumably be attributed to the proportion of shallow traps with a higher oxidation ability because . OH formation requires higher oxidation potential than O 2 evolution (2.83 and 1.23 eV vs. NHE, respectively) . Nonetheless, STH on the (111) facets are less stable, resulting in facile charge recombination.…”

“…Here, we first demonstrated the presence and distribution of different trap sites on the (100) and (111)f acets of Ag 3 PO 4 .T he different photocatalytic activities of the (111)a nd (100) facets to generate COH and O 2 (Figure 1d and e) can presumably be attributed to the proportion of shallow traps with ah igher oxidation ability because COH formation requires highero xidation potentialt han O 2 evolution (2.83 and 1.23 eV vs. NHE, respectively). [17] Nonetheless,S TH on the (111)f acets are less stable, resultingi nf acile charge recombination. These results indicate at rade-off relationship between charge-carrier lifetime and photocatalytic activity;l ong-lived chargec arriers are sometimes too stable to react.…”