Photocatalytic Activity Suppression of Ag₃PO₄-Deposited Cu₂O Octahedra and Rhombic Dodecahedra

Abstract

Ag3PO4 nanoparticles were lightly deposited on Cu2O cubes, octahedra, and rhombic dodecahedra for facet-dependent photocatalytic degradation of methyl orange. Cu2O cubes remain inactive after loading with Ag3PO4. Drastic photocatalytic activity suppression occurs for Ag3PO4-decorated Cu2O octahedra. Surprisingly, total deactivation results for Cu2O rhombic dodecahedra after Ag3PO4 deposition. Electron paramagnetic resonance spectra and electrochemical impendence measurements support the experimental observations. Interfacial Ag3PO4 lattice planes have been identified. A modified band diagram is constructed to understand photocatalytic activity decay or deactivation because of large interfacial band bending to create an unfavorable situation for charge carrier transport across the heterojunctions. This study further illustrates that photocatalytic suppression can be often observed in many semiconductor heterojunctions and multiple interfacial plane combinations mean that photocatalytic outcomes are unpredictable.

Current Rectification and Photo-Responsive Current Achieved through Interfacial Facet Control of Cu2O–Si Wafer Heterojunctions

“…The idea of a thin surface layer with tunable degrees of band bending was adopted to understand the strong facet dependence in photocatalytic activity. Remarkably, when other semiconductor particles including ZnO, ZnS, CdS, and Ag 3 PO 4 are deposited on Cu 2 O polyhedra, in many cases, photocatalytic activity suppression to the degree of complete deactivation can happen instead of the expected activity enhancement on the basis of band energy alignment analysis for the semiconductor heterojunctions. − We can understand these observations because both favorable and mismatched interfacial band bending can happen depending on the contacting lattice planes between the two semiconductor materials. Thus, one can extend the surface layer idea to semiconductor interfaces.…”

Facet-Specific Photocatalytic Activity Enhancement of Cu2O Polyhedra Functionalized with 4-Ethynylanaline Resulting from Band Structure Tuning

“…The photocatalytic inactivity of Cu 2 O cubes was established because Cu 2 O nanocubes decorated with gold nanoparticles remained inactive, whereas Cu 2 O octahedra and rhombic dodecahedra recorded the expected photocatalytic enhancement due to more efficient charge carrier separation . Beyond metal particle decoration, deposition of ZnO, ZnS, CdS, and Ag 3 PO 4 particles on Cu 2 O cubes still did not show any photocatalytic activity, despite their favorable band energy alignments to facilitate charge carrier separation, whereas these semiconductor heterostructures yielded both photocatalytic enhancement and suppression on Cu 2 O octahedra and rhombic dodecahedra. ,− Different combinations of contacting lattice planes at the heterojunctions producing varying degrees of interfacial band bending are believed to cause such unexpected photocatalytic behaviors. The next type of interesting photocatalytic system is surface modification with conjugated molecules as a charge transport mediator.…”

Dynamic growth of rhombic dodecahedral Cu2O crystals controlled by reaction temperature and their size-dependent photocatalytic performance

“…1 Various experiments regarding visible-light photodegradation of different categories of organic dyes have been reported. 2 Cuprous oxide (Cu 2 O) 3,4 and its complexes (such as heterostructures [5][6][7][8][9] and plasmonic [10][11][12][13] forms) represent important visible-light photocatalysts, and have been widely applied in photocatalytic degradation of organic pollutants.…”