Building heterojunctions and exposing more catalytic active sites are effective strategies to enhance the photocatalytic hydrogen evolution activity. Herein, TiO 2 nanosheets are oxidized in situ on Ru-loaded MXene as carriers and subsequently loaded with uniform 2D CdS via hydrothermal method to obtain 2D Ru/Ti 3 C 2 -TiO 2 /CdS composite photocatalysts that integrate heterojunctions and cocatalysts. The formation of heterojunction between CdS and TiO 2 is conducive to promoting the separation and transfer of photogenerated charges, simultaneously, Ru/Ti 3 C 2 with the fully exposed Ru and Ti 3 C 2 can act as effective active sites of photocatalytic hydrogen production reaction. The composite photocatalyst exhibits an improved hydrogen production rate with 5479 µmol g −1 h −1 , which is 5, 3, and four times more than that of pristine CdS, CdS loaded Ti 3 C 2 -TiO 2 and CdS loaded Ru-TiO 2 respectively. The results reveal that the notable enhancement in performance can primarily be ascribed to the introduction of the TiO 2 /CdS heterojunction and the efficient cocatalysts of Ru/Ti 3 C 2 . Moreover, the 2D Ti 3 C 2 with high conductivity as carriers can increase charge transfer, and its 2D structure can serve as a template for growing 2D photocatalysts with higher activity. The interface engineering with multiple interfaces can offer novel insights for the advancement of efficient hydrogen evolution reaction catalysts.
Fangjie Han,Zhongqian Song,Jianan Xu,Mengjiao Dai,Shulin Luo,Dongxue Han,Li Niu,Zhenxin Wang
Antioxidants can protect organization from damage by scavenging of free radicals . When two kinds of antioxidants are consumed together, the total antioxidant capacity might be enhanced via synergistic interactions. Herein, we develop a simple, direct, and effective strategy to quantify the synergistic interaction between ascorbic acid (AA) and other different antioxidants by photoelectrochemical (PEC) technology. MXene Ti 3 C 2 –TiO 2 composites fabricated via hydrogen peroxide oxidation were applied as sensing material for the antioxidants interaction study. Under excitation of 470 nm wavelength, the photogenerated electrons transfer from the conduction band of TiO 2 nanoparticles to the Ti 3 C 2 layers, and the holes in TiO 2 can oxidize antioxidants, leading to an enhanced photocurrent as the detection signal. This PEC sensor exhibits a good linear range to AA concentrations from 12.48 to 521.33 μM as well as obvious antioxidants capability synergism. In particular, the photocurrents of AA + gallic acid (GA) and AA + chlorogenic acid (CHA) mixtures at 476.19 μM increase 1.95 and 2.35 times respectively comparing with the sum of photocurrents of AA and GA or CHA. It is found that the synergistic effect is mainly depending on the fact that AA with the low redox potential (0.246 V vs NHE) can reduce other antioxidants radical to promote regeneration , improving the overall antioxidant performance. Moreover, it is proved that the greater redox potential of antioxidants, the more obvious the synergistic effect. In addition, the sensor was used to real sample assay, which provides available information towards food nutrition analysis, health products design and quality inspection.
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