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Recently， approximately 20% of the products unqualified in the national sampling inspection of imported food have been found through food label inspection， which has become one of the most important inspection methods for imported prepackaged food. In this study， the labels of imported prepackaged food were analyzed to determine the important inspection points， noting that particular attention should be paid to the conformity of products with the entry and registration requirements of the general administration of customs， the use of compliant raw materials， and the standardization of the special labeling content. The results suggest that the quality and efficiency of label inspection should be improved from four aspects： enhancing the awareness and ability to prevent and control unqualified risks， strengthening the training of inspectors’ professional skills， developing an artificial intelligence label verification system， and optimizing the relevant laws and standards to improve the safety of imported prepackaged food.

CuBi2O4 is a promising p-type semiconductor material with a theoretical maximum current density of about 19.7 mA cm‒2. Although CuBi2O4 has a very high theoretical photocurrent, its poor charge transmission efficiency makes its actual photocurrent far less than its theoretical values. Herein, an in situ modification method is adopted to prepare a photocathode material with Ag as conductive channels. A metal–organic coating method is used to introduce Ag conductive channels, promoting the charge transmission between grains. Ag particles play the role of electrical connection, and improve the separation and transmission of carriers, so as to obtain enhanced photocurrent density. In situ formed Ag conductive channels significantly enhanced the PEC performance of CuBi2O4 photocathodes. [ABSTRACT FROM AUTHOR]

BiVO4 possesses a suitable band gap for photoelectrochemical (PEC) water splitting to produce hydrogen; however, the performance of BiVO4 is limited by several adverse factors. The bulk charge recombination and the slow surface water oxidation reaction of BiVO4 are main unfavorable factors. In view of these disadvantages, an Fe–Bi electrocatalyst is loaded on BiVO4 to improve the PEC performance of BiVO4. After modification, the onset potential of BiVO4 shifts negatively by 60 mV, and the saturated photocurrent is greatly increased. Systematic studies demonstrate that the Fe–Bi electrocatalyst not only enhances the bulk charge separation, but also accelerates the surface water oxidation rate of BiVO4 and greatly reduces the resistance of the reaction interface. [ABSTRACT FROM AUTHOR]

Passivating surface traps plays a crucial role in mitigating the efficiency loss of solar water-splitting electrodes. However, the associated surface-trap passivation approaches require the introduction of an overlayer, complicating the fabrication process and increasing the capital cost of photoelectrodes. Herein, using CuBi2O4 as a prototype, an in situ surface-trap passivation strategy is developed, which yields a beneficial 90 mV anodic shift in hydrogen-evolution onset. Detailed mechanism investigations prove that the intentionally added Mg2+ ions in the precursor gradually segregate as MgO and enrich at the grain boundaries/surface of the CuBi2O4 multicrystalline, porous film during annealing, via which surface traps stemming from dangling bonds are spontaneously passivated; measurements of photovoltage generation characteristics and carrier lifetime validate the favorable roles of the MgO passivator in CuBi2O4 photocathodes. A bias-free water-splitting device is assembled using MgO-passivated CuBi2O4 and Mo-doped BiVO4 as the photocathode and photoanode respectively in a tandem configuration, delivering a solar-to-hydrogen conversion efficiency of approximately 0.41%. [ABSTRACT FROM AUTHOR]

Exploring cheap and efficient cocatalysts is particularly important for a photoanode during photoelectrochemical (PEC) water splitting. Herein, we demonstrate that composite CoOx/CuO cocatalyst could efficiently enhance the oxygen evolution activity of BiVO4. The onset potential of BiVO4 shifts negatively from 0.42 to 0.38 V vs. the reversible hydrogen electrode (RHE), and the photocurrent of BiVO4 increases from 0.42 mA cm−2 to 1.58 mA cm−2 at 1.23 V vs. RHE, which increases by about 3.76 times. It was confirmed by subsequent electrochemical and physical characterization that the charge separation and injection efficiency were improved, and the IPCE was also improved. Systematic studies indicate that composite CoOx/CuO cocatalyst exhibits better performance than the single CoOx or CuO cocatalyst for promoting the separation of electron‐hole, and accelerating the surface water oxidation reaction. [ABSTRACT FROM AUTHOR]

Photocatalytic removal of hexavalent chromium (Cr(VI)) based on semiconductor is important under visible light for environment and energy. Herein, a visible light-responsive heterojunction composed of molybdenum disulfide and zinc indium sulfide was synthesized through a simple one-pot hydrothermal method to ensure full contact between the two components to efficiently improve the Cr(VI) reduction. The MoS2/ZnIn2S4 composites build heterojunctions between MoS2 and ZnIn2S4 to inhibit recombination of photogenerated holes and electrons and provide the reaction sites to trap photogenerated electrons to participate in the reduction of Cr(VI). The highly efficient reduction of Cr(VI) was obtained by adjusting the proportion of molybdenum disulfide. It demonstrates that the 0.5 wt% MoS2/ZnIn2S4 composite microstructures show the highest degradation rate of 0.1989 s−1 under visible light irradiation, 1.7 times of bare ZnIn2S4. Moreover, the MoS2/ZnIn2S4 showed excellent stability during photocatalytic recyclable processes. This work encourages researchers to remove Cr(VI) by constructing effective heterojunction structures. [ABSTRACT FROM AUTHOR]

With the dramatic increase in the application of modern office equipment, such as laser printers and photocopiers, large amounts of waste toner powder are used and discarded, ending up in landfills around the world. As waste toner powder contains hazardous compounds that can seriously endanger both the environment and human health, it is urgent to deal with waste toner powder and convert it into high value-added products. In this work, we report, for the first time, visible-light-driven hydrogen production with waste toner activated by cheap Ni species (waste toner@Ni-species) as the photocatalyst. The Ni species adhered to the waste toner through in situ photoreduction, without sophisticated equipment. It is found that the Ni species were composed of metallic Ni and oxidized Ni, which worked in synergy to remarkably enhance the photocatalytic activity of the waste toner. Activated by the Ni species, the hydrogen evolution rate of the waste toner was accelerated by up to 62 times, and the apparent quantum efficiencies (AQEs) of the waste toner were boosted by up to 64 times. In addition, the waste toner@Ni-species exhibited a higher charge separation efficiency, faster interfacial charge transfer rate and ∼200 mV lower barrier for proton reduction than those of the pristine waste toner. In addition to these merits, the waste toner@Ni-species could be separated conveniently from the aqueous system using magnetic attraction, as the saturation magnetization and residual magnetism of the waste toner were improved with the assembly of the Ni species. The approach shown here indicates a simple and promising way to deal with waste toner by converting it to a cost-effective photocatalyst for producing clean energy. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) water splitting can convert solar energy into clean and renewable hydrogen energy, showing a promising application prospect. However, large‐scale implementation of PEC water splitting is now hampered by insufficient solar‐to‐hydrogen conversion efficiency, which requires the development of high‐performance photoelectrodes. Key processes that determine the water splitting performance of photoelectrodes are the light absorption, separation, and transport efficiency of photogenerated electrons and holes and the surface reaction of water oxidation/reduction. Concerning these three key processes, various material design and surface/interface engineering strategies have been explored to improve the performance of photoelectrodes. Herein, these strategies for photoelectrode optimization of the past decades are summarized and discussed in terms of micro‐ and nanostructuring, heterojunction construction, element doping, surface passivation, plasmonic metal coating, and electrocatalyst modification. Special attention is given to how these strategies play their roles in improving the performance of photoelectrodes, based on which it is hoped light is shed on the design principles and modification routes for high‐performance photoelectrodes. [ABSTRACT FROM AUTHOR]

For a photoanode, a large overpotential for water oxidation, which limits the solar-to-hydrogen efficiency, may be caused by slow water oxidation kinetics and the recombination of photo-induced electrons and holes. Herein, taking flat and thin BiVO4 photoanodes as an example, the composite AgOx/NiOx electrocatalyst was found to promote not only the water oxidation kinetics, but also the bulk charge separation. As a result, the surface charge injection efficiency (ηinj) and the bulk charge separation efficiency (ηsep) of BiVO4 photoanodes were improved by the composite AgOx/NiOx electrocatalyst. Photo-assisted electrochemical impedance spectroscopy (EIS) was employed to illustrate the significantly reduced surface charge transfer resistance of the BiVO4/AgOx/NiOx sample at the interface between the photoanode surface and the electrolyte. Analysis of the surface potential changes obtained from photo-assisted Kelvin probe force microscopy (KPFM) revealed that the surface photovoltage (SPV) of the BiVO4/AgOx/NiOx photoanode is higher than those of BiVO4/AgOx and BiVO4/NiOx, representing its large band bending region for bulk charge separation. The open circuit photovoltage (OCP) measurements also demonstrated the superior charge separation ability of the BiVO4/AgOx/NiOx photoanode. The possible working mechanism is that one component of the composite AgOx/NiOx electrocatalyst may stabilize the high valence states of the other metal ions, which is beneficial for the formation of water oxidation active sites and the extension of the band bending region. [ABSTRACT FROM AUTHOR]

BiVO has emerged as a promising material for solar water splitting. The poor ability of charge transport and separation always limits its performance for photoelectrochemical water splitting. Herein, we coupled n-type BiVO with p-type LaFeO and LaCoO, achieving a photocurrent more than two times as high as bare BiVO at 1.23 V versus a reversible hydrogen electrode. Also, the onset potential was negatively shifted about 260 mV. The promotion of performance is mainly because the space charge layer in BiVO is broadened, and the band bend is enhanced, which facilitates the separation and transport of photo-generated charges. [ABSTRACT FROM AUTHOR]

Bismuth vanadate photoanodes often suffer from poor electron transport, which restricts their photoelectrochemical performance in water oxidation. Here, reduced graphene oxide sheets with excellent electronic conductivity are introduced to bismuth vanadate photoanode films to provide a channel for electron transport. As a result, the charge separation efficiency of the photoanode films increases from 59 to 78 % at 420 nm and 1.23 V (vs. the reversible hydrogen electrode) under back irradiation. In particular, the onset potential for photoelectrochemical water oxidation over reduced graphene oxide-bismuth vanadate photoanode films has a cathodic shift of approximately 120 mV in potassium borate electrolyte compared to bare bismuth vanadate photoanode films. [ABSTRACT FROM AUTHOR]