Enhanced Photoelectrochemical Performance by Interface Engineering in Ternary g‐C₃N₄/TiO₂/PbTiO₃ Films

Abstract

Ferroelectric materials recently rise as promising candidates in solar energy harvesting owing to their unconventional photophysics, such as above-bandgap photovoltage, [6] tunable photovoltaic outputs, and birefractive behaviors. [7] These unique properties stem from the centrosymmetry breaking and spontaneous polarization of ferroelectrics, which produces an internal field that drives the efficient separation of photocarriers. [8] PbTiO 3 (PTO), as a prototypical ferroelectric perovskite oxide, stands out as a potential material for PEC applications due to its robust room temperature ferroelectricity and huge polarization. [9] Also, noble-metal decoration or other semiconductors compositing were used to further improve the PEC performance of PTO. For example, Chao et al. utilized a hydrothermal method to synthesize Au island decorated single-domain PTO nanoplates, and the composite demonstrated an efficient photocatalytic degradation of RhB performance. [10] Lekha et al. engineered a series of PTO/LaCrO3 p-n junction through a two-step combustion process, and found that the optimal photocurrent density was 4.5 times larger than that of pure PTO photoelectrode. [11] Recently, metal-free polymeric semiconductor, graphitelike carbon nitride (g-C 3 N 4 ) has attracted much attention due to its moderate band gap of 2.7 eV and inherent chemical and thermal stability compared to transitional metal oxides and sulfide. [12] However, the high photocarrier recombination rate and poor quantum efficiency has driven the effort to construct various composite structures to alleviate these deficiencies of pure g-C 3 N 4 . [13] Xiao et al. fabricated a Z-scheme 0D g-C 3 N 4 particles/1D TO nanotube arrays heterostructure to promote charge carriers separation and transfer processes, thus improve the PEC water splitting ability. [14] Wang et al. prepared a nanostructured g-C 3 N 4 /BiVO 4 composite films, and the photocurrent density was approximately 15 times as that of BiVO 4 photoelectrode, which was ascribed to the formation of a type II heterostructure between g-C 3 N 4 and BiVO 4 . [15] In this study, we fabricated the polycrystalline PTO film by a sol-gel method, and the g-C 3 N 4 were than decorated on the surface of the PTO film through chemical vapor deposition method to improve the PEC performance. To further improve the PEC performance, a TO buffer layer was inserted between PTO and g-C 3 N 4 , which was widely used as electrons transport layer in solar cells. [16] The optimal photocurrent density of CN/TO/PTO photoelectrode was 4.5 times higher than that Polycrystalline ferroelectric PbTiO 3 (PTO) films deposited on transparent fluorine-doped tin oxide (FTO) glass have been proved to be a photocathode for photoelectrochemical (PEC) water splitting. However, the hitherto reported PEC performances remain inferior to meet the requirements for practical applications. Herein, it is reported that a compact TiO 2 (TO) buffer layer, inserted between PTO and g-C 3 N 4 (CN), improves significantly its PEC performance. The o...

Highly transparent Bi4Ti3O12 thin-film electrodes for ferroelectric-enhanced photoelectrochemical processes

“…Open ). This phase, which has often been observed both in Bi 4 Ti 3 O 12 powder samples and films [52][53][54][55][56][57][58][59][60][61][62][63][64] depending on synthesis temperature, Bi:Ti molar ratio, substrate, and film growth condition, has been proven to decompose at temperatures higher than 600°C ( †ESI, Figure S1), in accordance with the literature. 65 However, such heating conditions cannot be employed in the fabrication of the BiTO layers due to the use of FTO-coated glass substrates ( †ESI, section S1).…”

“…A lot of work has been published on the study and development of poled ferroelectric photoelectrodes such as BiFeO 3 , [31][32][33][34][35][36][37][38][39][40] BaTiO 3 , [41][42][43][44][45] Li/Na/K-NbO 3 , [45][46][47][48][49] PbTiO 3 -PbZrTiO 3 , [50][51][52][53] and SrTiO 3 , 54,55 for the PEC water-splitting reaction, but the use of ferroelectric photocathodes for CO 2 PEC reduction has not been exploited yet. On the other hand, some studies on the production of BiTO ferroelectric layers have been reported for photovoltaic applications, [56][57][58] and only one preliminary work on photo-electrocatalysis has been reported, where thin lm BiOI/BiTO electrodes were fabricated via a metering rod method for the photo-electrochemical characterization of this heterostructure, as a photoanode in the ferroelectric-assisted water-splitting reaction.…”

Modulation of Bipolar Ultraviolet Current in TiO2 Nanofilms for Switching Logic Devices via Ti Valence State Control

“…The principle of photoelectron chemistry operates by following conventional solid-state photodetectors’ typical carrier generation, separation, and migration processes. − However, it also involves a distinctive electrochemical process, which includes ion diffusion processes at the semiconductor–electrolyte interface and redox reactions in solution. Importantly, the polarity of the photocurrent in a PEC device can be altered by changing the wavelength of the incident light or the applied bias potential, a phenomenon referred to as PEC photocurrent switching (PEPS). − This modulation is achieved by artificially controlling the carrier migration and transport processes within PEC devices, resulting in a positive or negative photocurrent direction. This forms the foundation for utilizing PEC devices in logic gates, photo convulsions, and other information devices. , …”

Photoelectrochemical properties of TiO2/g-C3N4 composited electrodes fabricated by a co-electrodeposited method

“…Recently, the metal-free polymer graphitic carbon nitride (g-C 3 N 4 ) has been intensively studied for photocatalytic water splitting due to its appropriate band gap, high chemical stability [11], visible light response, high earth abundance, and non-toxic elements [12][13][14]. However, pristine g-C 3 N 4 has been rarely reported as photoelectrode due to its poor electron and hole conductivity and low quantum efficiency (IPCE) [15,16]. Great efforts have been made to improve the performance of pristine g-C 3 N 4 by developing new composite electrode materials.…”