Efficient all-in-one removal of total chromium over nonconjugated polymer-inorganic ZnIn2S4 semiconductor hybrid

Photocatalytic production of a C12 liquid biofuel precursor and H2 by Ni(OH)2-ZnIn2S4 in anaerobic water

Herein, we presented a bifunctional photocatalytic system for 5-hydroxymethylfurfural (HMF) valorization over Ni(OH)2-modified ZnIn2S4. Instead of forming 2,5-diformylfuran C6 products from conventional HMF aerobic oxidation, C-C coupling C12 products and H2 were produced in anaerobic water, which can be an important liquid fuel intermediate and gaseous energy carrier, respectively. This work could spark more insight for biomass utilization.

Ni(OH)2 surface-modified hierarchical ZnIn2S4 nanosheets: dual photocatalytic application and mechanistic insights

The simultaneous utilization of electrons and holes to couple photocatalytic H2 production with selective biomass transformation has attracted immense interest toward achieving sustainability in the fields of energy and chemical industry. In this study, by assembling highly dispersed Ni(OH)2 onto ZnIn2S4 (ZIS), efficient H2 evolution along with highly selective photocatalytic oxidation of furfuryl alcohol (FA) to furfural (FF) in pure water was achieved under anaerobic conditions. The H2 production and FA conversion rates over the optimal Ni-ZIS sample reached about 686 and 583 μmol g-1 h-1, respectively, about 4.9 and 1.7 folds as those of pure ZIS. Moreover, the formation of by-products with C-C coupling was dramatically suppressed over Ni-ZIS, resulting in higher selectivity for FF (97%), which is about 2.7-fold that of pure ZIS (36%). Deep mechanistic studies were conducted to reveal the structural evolution and cocatalyst effects of Ni(OH)2. This study not only offers a feasible paradigm for modifying the surface of catalysts to tune the photoactivity and selectivity for product-oriented alcohol oxidation coupled with efficient H2 production in water but also reveals the working mechanism of the deposited Ni(OH)2 over ZIS toward coupling reactions.

Chemical bonding and facet modulating of p-n heterojunction enable vectorial charge transfer for enhanced photocatalysis

Heterojunctions have been proved to be the promising photocatalysts for hazardous contaminants removal, but the inferior interfacial contact, low carrier mobility and random carrier diffusion seriously hamper the photoactivity improvement of the conventional heterojunctions. Herein, SO chemically bonded p-n oriented heterostructure is fabricated via selectively anchoring of p-type Ag2S nanoparticles on the lateral facet of n-type Bi4TaO8Cl nanosheet. Such a p-n heterojunction engineering on specific facet of Bi4TaO8Cl semiconductor derives ingenious double internal electric field (IEF), which not only effectively creates the spatially separated oxidation and reduction sites, but also delivers the powerful driving forces for impactful spatial directed photocarrier transfer along the cascade path. Additionally, our experimental and theoretical analyses jointly signify that the interfacial SO bond could serve as an efficient atomic-level interfacial channel, which is conducive to encouraging the vectorial charge separation and migration kinetic. As a result, the Ag2S/Bi4TaO8Cl oriented heterojunction exhibits significantly enhanced visible light driven photocatalytic redox ability for tetracycline oxidation and hexavalent chromium reduction than those of single component and the traditional random/mixed heterojunctions. This study could provide a deeper insight into the synergistic effects of multi-IEF modulation and interfacial chemical bond bridging on optimizing the photogenerated carrier behaviors.

In-situ preparation of mossy tile-like ZnIn2S4/Cu2MoS4 S-scheme heterojunction for efficient photocatalytic H2 evolution under visible light

The reasonable design and fabrication of heterojunction could regulate the photocatalytic performance to some extent, yet it is still a great challenge to construct the S-scheme heterostructure with the stable as well as tight interface on the surface of semiconductor photocatalysts. Herein, the ZnIn2S4/Cu2MoS4 (ZIS/CMS) S-scheme heterostructure was fabricated by in-situ assembling ZIS nanosheets on the CMS plates, obtaining a mossy tile-like morphology. Owing to the compact interface resulting from in-situ growth, this unique architecture efficiently facilitated the separation and transfer of light-induced charges, guaranteed the larger interface area, and enriched the active sites for photocatalytic redox reactions. After adjusting the mass ratio of CMS in ZIS/CMS, S-scheme heterostructure exhibited the remarkable performance with an optimal H2 producing rate up to 1298 μmol·h-1 g-1, about 13.8 times than that of pristine ZIS. The mechanism and driving force of charge transfer and separation in S-scheme heterostructure photocatalysts were explained and discussed. This investigation will provide new insight into design and construction of S-scheme heterojunction photocatalysts for H2 evolution.

Effect of Ag Modification on the Structure and Photocatalytic Performance of TiO2/Muscovite Composites

Ag/TiO2/muscovite (ATM) composites were prepared by the sol–gel method and the effects of Ag modification on the structure and photocatalytic performance were investigated. The photocatalysts were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller surface area (BET), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), photoluminescence spectra (PL) and ultraviolet–visible diffuse reflectance spectra (DRS). The photocatalytic activity of the obtained composites was evaluated by taking 100 mL (10 mg/L) of Rhodamine B (RhB) aqueous solution as the target pollutant. The muscovite (Mus) loading releases the agglomeration of TiO2 particles and the specific surface area increases from 17.6 m2/g (pure TiO2) to 39.5 m2/g (TiO2/Mus). The first-order reaction rate constant increases from 0.0009 min−1 (pure TiO2) to 0.0074 min−1 (150%TiO2/Mus). Ag element exists in elemental silver. The specific surface area of 1-ATM further increases to 66.5 m2/g. Ag modification promotes the separation of photogenerated electrons and holes and increases the visible light absorption. 1%Ag-TiO2/Mus (1-ATM) exhibits the highest photocatalytic activity. After 100 min, the rhodamine B (RhB) degradation degrees of PT, 150%TiO2/Mus and 1-ATM are 10.4%, 48.6% and 90.6%, respectively. The first-order reaction rate constant of 1-ATM reaches 0.0225 min−1, which is 25 times higher than that of pure TiO2.

Removal of Tetracycline Hydrochloride by Photocatalysis Using Electrospun PAN Nanofibrous Membranes Coated with g-C3N4/Ti3C2/Ag3PO4

In order to improve the photocatalytic performance of g-C3N4, the g-C3N4/Ti3C2/Ag3PO4 S-type heterojunction catalyst was prepared by electrostatic assembly method, and then the g-C3N4/Ti3C2/Ag3PO4/PAN composite nanofiber membrane was prepared by electrospinning technology. The morphology and chemical properties of the nanofiber membrane were characterized by SEM, FTIR, and XRD, and the photocatalytic degradation of tetracycline hydrochloride (TC) in water by the nanofiber membrane was investigated. The results showed that g-C3N4/Ti3C2/Ag3PO4 could be successfully loaded on PAN and uniformly distributed on the surface of composite nanofiber membrane by electrospinning technology. Increasing the amount of loading and catalyst, lowering the pH value and TC concentration of the system were conducive to the oxidation and degradation of TC. The nano-fiber catalytic membrane had been recycled five times and found to have excellent photocatalytic stability and reusability. The study of catalytic mechanism showed that h+, •OH and •O2− were produced and participated in the oxidation degradation reaction of TC, and •O2− plays a major role in catalysis. Therefore, this work provides a new insight into the construction of high-performance and high-stability photocatalytic system by electrospinning technology.