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

Abstract

Silver phosphate (Ag PO ) is a promising visible-light-driven photocatalyst with a strong oxidation power and exceptionally high apparent quantum yield of O evolution. Although engineering Ag PO facets is widely known to enhance its photocatalytic activity, most studies have explained its facet effect by calculating surface energies. Herein, the charge carrier dynamics in three kinds of Ag PO crystals (mixed facets, cubic, and tetrahedral structures) were first investigated using single-particle photoluminescence microscopy and femtosecond time-resolved diffuse reflectance spectroscopy. As a result, we clarified that the disagreement between the photocatalytic activities (dye degradation and O evolution) of different Ag PO facets are the consequence of trade-off between catalytic activity and lifetime of photogenerated charge carriers in addition to surface energy.

Prominent roles of Ni(OH)2 deposited on ZnIn2S4 microspheres in efficient charge separation and photocatalytic H2 evolution

“…[4][5][6] Unfortunately, the direct application of these semiconductors themselves for photocatalytic H 2 production is almost infeasible mainly due to their rapid charge recombination. [7][8][9] For an efficient photocatalytic H 2 production reaction, it is indispensable to load a noble metal such as Pt, Pd, Ag, or Au as a cocatalyst on the host semiconductors. [10][11][12][13] The noble metals as cocatalysts can not only facilitate the separation of electron-hole pairs over host semiconductor effectively, but also function as active sites for H 2 production.…”

Bi‐based photocatalysts for light‐driven environmental and energy applications: Structural tuning, reaction mechanisms, and challenges

“…The exploitation of photocatalysts is one of the keys to realize the high‐performance application of photocatalytic technology 10‐12 . Up to now, various semiconductor photocatalysts have been developed, including metal oxides (TiO 2 , Bi 2 O 3 , etc), 13‐16 metal sulfides (MoS 2 , Bi 2 S 3 , etc), 17‐21 multi‐component oxides (Bi 2 WO 6 , SrTiO 3 , etc), 22‐25 metal selenides (MoSe 2 , CdSe, etc), 26‐29 metal phosphides (Co 2 P, Ni 2 P, etc), 30‐32 metal phosphates (Ag 3 PO 4 , BiPO 4 , etc), 33,34 metal halides (AgBr, etc), 35‐37 metal oxyhalides (BiOBr, BiOCl, etc), 38‐40 metal‐free materials (SiC, g‐C 3 N 4 , etc) 41‐43 and so on. Among them, the semiconductor with a band gap of Eg ≥ 3 eV are called wide‐band‐gap photocatalysts.…”

Charge carrier dynamics and photocatalytic activity of {111} and {100} faceted Ag3PO4 particles

“…The lower photocatalytic performance for the tetrahedral particles in this study as compared to that obtained by Martin et al has also been observed in other studies with comparable or even lower photocatalytic performance when compared to the cubic particles. 15,20 In our study, we relate the lower oxygen evolution rate mainly to the lower illumination intensity (100 mW cm -2 in this study versus 500 mW cm -2 in Martin et al 9 ). Previous work on the relation of photocatalytic reaction rate and light intensity shows a linear relationship at lower light intensities which then saturates at higher intensities.…”

“…While the {111} particles have a highly P-rich surface, the {100} particles showed a slightly Ag-rich surface. The highly P-rich surface of the tetrahedral particles has been shown theoretically to lead to the presence of 'dangling' P-O bonds 7,15 . DFT calculations showed that these dangling bonds can enhance the photocatalytic activity of the tetrahedral surface 6 , since they demonstrate low free energy change for the dehydrogenation of water molecules, which is the first step in the oxygen evolution reaction 7 .…”

“…In contrast to the various theoretical studies on this topic, only one experimental work has previously attempted to explore the effect of different facets on the charge carrier dynamics and photocatalytic properties 15 . In that study, lower photocatalytic activity and charge carrier lifetime was found for the tetrahedral as compared to the cubic Ag 3 PO 4 .…”