A novel H2O2photoelectrochemical sensor based on ternary RGO/Ag-TiO2 nanotube arrays nanocomposite

ACS Appl. Energy Mater.

et al. 2022

Transition metal (oxy)hydroxides are recognized as the most effective non-noble metal electrocatalysts for the alkaline oxygen evolution reaction (OER). However, their electrical conductivity and durability are insufficient for the development of electrochemical energy devices. Thus, constructing more compact and stable transition metal-based composite materials while maintaining high activity is still desperately needed. In this study, we propose a potent approach for producing highly active sites via alloying transition metals with carbon elements evolved from the MAX phases. We for the first time found an activation paradigm for such a phase (V2(Co x Sn1‑x )C) via an OER in situ polarization process. The mechanism is proposed as the Co element in the A site significantly facilitates the structural evolution of the pristine V2SnC phase. Compared with typical electrodeposited cobalt hydroxide (Co–H), such a MAX-derived catalyst exhibits better OER activity and lower valence charge transition potential owing to its unique nanocomposite structure, more exposed active sites, and better electric conductivity. Furthermore, the preparation of this catalyst is applicable to nickel foams. Our investigation confirmed its long-term stability and superior activity over most reported Co-based catalysts. This unique structural evolution route provides a potentially generalizable strategy for MAX phases as efficient electrocatalysts.

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Excellent CoO_xH_y/C Oxygen Evolution Catalysts Evolved from the Rapid In Situ Electrochemical Reconstruction of Cobalt Transition Metals Doped into the V₂SnC MAX Phase at A Layers

Zhu

ACS Appl. Energy Mater.

et al. 2022

“…The corresponding equivalent electrical circuit and fitting parameters are presented in Figure b and Table S3, respectively, where R ct signifies the charge transfer resistance at the electrode/electrolyte interface, R sc represents the space charge layer resistance at the space charge layer near the surface of electrodes, and R s and CPE are the solution resistance and constant phase element representing the pseudocapacitive behavior of each interface/EC process, respectively. The smaller arc radius means smaller resistance and higher charge transfer efficiency. − Here, the α-SnWO 4 /CoO x photoanode ( R ct + R sc = 3.0 kΩ) possesses better photogenerated charge transport kinetics than the pristine α-SnWO 4 film ( R ct + R sc = 9.1 kΩ). The corresponding Bode plots (Figure S22) also consistently show this improvement of charge transport kinetics between samples.…”

Section: Resultsmentioning

confidence: 99%

Chemical Vapor Deposition of Crystalized Nanoscale α-SnWO₄ Thin Films and Their Photoelectrocatalytic Properties

Zhu

ACS Appl. Energy Mater.

et al. 2022

Photoelectrochemical (PEC) systems provide a cost-effective strategy to harvest solar power into green fuels and valuable chemicals. Among various candidate materials for the light-absorbing layer in PEC photoanodes, n-type α-SnWO 4 is quite attractive owing to its favorable band positions and decent visible light absorption. Although thin films are the most widely reported type of PEC photoelectrodes, up to now, only very few physical deposition techniques were realized for α-SnWO 4 PEC structures. Herein, we demonstrate a chemical vapor deposition (CVD) strategy for high-quality α-SnWO 4 thin films for PEC applications. This route features unsophisticated instrumentation, and, more importantly, a chemical process uniformly reacting vaporized SnCl 2 with a predeposited WO 3 layer on substrates. Homogeneous and phase-pure thin films can be obtained with controllable thickness (260−560 nm) and excellent visible light absorption. The nanoscale film was confirmed with decent intrinsic structural durability, as confirmed by a stable PEC photocurrent output. We also tentatively demonstrated the successful surface modification of a catalytic overlayer on this nanoscale film, which is desired for the efficient extraction of charge carriers. This CVD route first demonstrates a paradigm for preparing metastable oxide thin films, which are of particular interest for PEC and other optoelectronic applications.

“…Titanium dioxide (TiO 2 ) is a widely studied photosensitive material owing to its favorable photoelectric properties, natural abundance, high photocorrosion resilience, and excellent biocompatibility. − The photoelectric performance of TiO 2 can be enhanced by altering its structure; for example, TiO 2 nanotube arrays (NTAs) display an enhanced electron transportation rate and PEC performance attributed to the dense pattern of aligned nanotubes and intimate contact with the Ti foil substrate. , However, the PEC application of intrinsic TiO 2 NTA is hindered by its wide band gap and rapid electron–hole recombination. The PEC efficiency of TiO 2 NTA can be improved through forming heterostructures with organic nanomaterials with narrow band gaps. − Gao et al constructed a γ-graphyne/TiO 2 NTA heterojunction using a facile drop-coating method.…”

Section: Introductionmentioning

confidence: 99%

“…12−15 The photoelectric performance of TiO 2 can be enhanced by altering its structure; for example, TiO 2 nanotube arrays (NTAs) display an enhanced electron transportation rate and PEC performance attributed to the dense pattern of aligned nanotubes and intimate contact with the Ti foil substrate. 16,17 However, the PEC application of intrinsic TiO 2 NTA is hindered by its wide band gap and rapid electron−hole recombination. The PEC efficiency of TiO 2 NTA can be improved through forming heterostructures with organic nanomaterials with narrow band gaps.…”

Section: ■ Introductionmentioning

confidence: 99%

Fluoro-Substituted Covalent Organic Framework Particles Anchored on TiO₂ Nanotube Arrays for Photoelectrochemical Determination of Dopamine

Wang

et al. 2021

ACS Appl. Nano Mater.

In this work, the photoelectrochemical (PEC) properties of TiO2 nanotube arrays (NTAs) were enhanced by forming heterostructures with non-substituted covalent organic frameworks (H-COFs) and fluoro-substituted covalent organic frameworks (F-COFs) through a facile in situ hydrothermal synthesis method. The composites H-COF/TiO2 NTA and F-COF/TiO2 NTA were fully characterized using scanning electron microscopy, energy-dispersive spectrometry, transmission electron microscopy, X-ray diffraction, attenuated total reflection–Fourier transform infrared, 13C CP/MAS NMR, and X-ray photoelectron spectroscopy. It was observed via UV–vis diffuse reflection spectroscopy that both H-COF/TiO2 NTA and F-COF/TiO2 NTA exhibited enhanced visible light absorption compared to bare TiO2. The modification of TiO2 with fluoro-substituted COF was found to be the most effective in enhancing the photoelectric response of TiO2 by producing photoelectrons with the longest lifetime based on the calculation of transient time constant (τ). The potential application of F-COF/TiO2 NTA as a PEC sensor for dopamine (DA) detection was investigated, and the resultant sensor exhibited an extended linear range for DA quantification (0.1–300 μM) with a detection limit of 0.032 μM (S/N = 3). The formation of a type II heterojunction was proposed to be responsible for the “signal on” mode for DA quantification using F-COF/TiO2 NTA.