Unveiling the charge transfer dynamics steered by built-in electric fields in BiOBr photocatalysts

Abstract

Construction of internal electric fields (IEFs) is crucial to realize efficient charge separation for charge-induced redox reactions, such as water splitting and CO2 reduction. However, a quantitative understanding of the charge transfer dynamics modulated by IEFs remains elusive. Here, electron microscopy study unveils that the non-equilibrium photo-excited electrons are collectively steered by two contiguous IEFs within binary (001)/(200) facet junctions of BiOBr platelets, and they exhibit characteristic Gaussian distribution profiles on reduction facets by using metal co-catalysts as probes. An analytical model justifies the Gaussian curve and allows us to measure the diffusion length and drift distance of electrons. The charge separation efficiency, as well as photocatalytic performances, are maximized when the platelet size is about twice the drift distance, either by tailoring particle dimensions or tuning IEF-dependent drift distances. The work offers great flexibility for precisely constructing high-performance particulate photocatalysts by understanding charge transfer dynamics.

Ultrafast carrier transport in ultrafine porous 2D polymers for the highly selective photocatalytic reduction of CO2to CH4

“…Although the adsorption capacity of the D1M2-PC sample is the highest due to its larger pore size, it also massively destroys the alternating D–A structure of the D1M2-PC sample, resulting in severely disrupted internal electric field and extremely low photoinduced carrier transport efficiency. 40 In situ FTIR can probe key intermediates on the surface of D1M4-PC samples for the CO 2 reduction reaction (Fig. 3h).…”

Uniting Heat and Light in Heterogeneous CO2 Photocatalysis: Optochemical Materials and Reactor Engineering

“…Then photogenerated electrons with a substantial reduction potential and holes with a significant oxidation potential migrate to the surface to induce redox reactions. 27 Meanwhile, these charge carriers inevitably experience recombination processes, which can be deleterious to the efficiency of photocatalysis. 28 The optoelectronic structure of indium oxide based-catalysts can be affected by their crystal phase, morphology, doping elements, and defect concentrations, which hugely determine the lifetime of photogenerated charge carriers and thus affect the photocatalytic activity.…”

“…Indium oxide, an archetypal n-type semiconductor with direct and indirect band gaps of 3.7 and 2.6 eV, respectively, exhibits photochemistry akin to other semiconductor materials in traditional photocatalysis. − Briefly, when the light with photon energy equal to or greater than the band gap energy irradiates a semiconductor, the valence band (VB) electrons are excited and move to the conduction band (CB) of the semiconductor, and leave the free holes in the VB. Then photogenerated electrons with a substantial reduction potential and holes with a significant oxidation potential migrate to the surface to induce redox reactions . Meanwhile, these charge carriers inevitably experience recombination processes, which can be deleterious to the efficiency of photocatalysis .…”

High-performance potassium poly(heptazine imide) films for photoelectrochemical water splitting

“…Solar-driven water splitting for hydrogen fuel production using a photoelectrochemical (PEC) platform is an appealing strategy by which to sustain energy demand. [1][2][3][4] In the PEC system, semiconducting photoelectrodes with the properties of the efficient absorption of visible light and high quantum yield have been researched for almost half a century, 5 and a variety of materials, including metal oxides, [6][7][8][9] metal oxynitrides, 10,11 perovskites, 12 polymers, 13 metal-organic frameworks [14][15][16] and other materials, [17][18][19][20][21] have been reported. Among them, conjugated polymers have received broad attention recently.…”