Synergistic interface phenomena between MOFs, NiPx for efficient hydrogen production

Synergistic removal of organic pollutants from water by CTF/BiVO4 heterojunction photocatalysts

Herein, a series of covalent triazine framework/bismuth vanadate (CTF/BiVO₄) heterojunction catalysts were prepared using the hydrothermal method. The mechanism of the CTF/BiVO₄ heterojunction photocatalyst in the system was examined to provide a theoretical basis for constructing a high-efficiency photocatalysis composite system for removing organic pollutants from water. Compared with CTF and BiVO₄ catalysts alone, composite materials have been shown to have significantly higher degradation efficiencies against organic pollutants in water. Moreover, the degradation effect was found to be optimal when the mass ratio of CTF to BiVO₄ was 1:1 (1-CTF/BiVO₄). On the basis of physicochemical characterization results, it was concluded that the effective construction of CTF/BiVO₄ composite photocatalyst material systems and the formation of type II heterojunction structures between CTF and BiVO₄ effectively promote the separation of photogenerated carriers and increase the interface charge transfer efficiency.

Synthesis and Characterization of Zn-Organic Frameworks Containing Chitosan as a Low-Cost Inhibitor for Sulfuric-Acid-Induced Steel Corrosion: Practical and Computational Exploration

In this work, a Zn-benzenetricarboxylic acid (Zn@H3BTC) organic framework coated with a dispersed layer of chitosan (CH/Zn@H3BTC) was synthesized using a solvothermal approach. The synthesized CH/Zn@H3BTC was characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), thermal gravimetric analysis (TGA), and Brunauer, Emmett, and Teller (BET) surface area. The microscopic observation and the analysis of the BET surface area of CH/Zn@H3BTC nanocomposites indicated that chitosan plays an important role in controlling the surface morphology and surface properties of the Zn@H3BTC. The obtained findings showed that the surface area and particle size diameter were in the range of 80 m2 g-1 and 800 nm, respectively. The corrosion protection characteristics of the CH/Zn@H3BTC composite in comparison to pristine chitosan on duplex steel in 2.0 M H2SO4 medium determined by electrochemical (E vs. time, PDP, and EIS) approaches exhibited that the entire charge transfer resistance of the chitosan- and CH/Zn@H3BTC-composite-protected films on the duplex steel substrate was comparatively large, at 252.4 and 364.8 Ω cm2 with protection capacities of 94.1% and 97.8%, respectively, in comparison to the unprotected metal surface (Rp = 20.6 Ω cm2), indicating the films efficiently protected the metal from corrosion. After dipping the uninhabited and protected systems, the surface topographies of the duplex steel were inspected by FESEM. We found the adsorption of the CH/Zn@H3BTC composite on the metal interface obeys the model of the Langmuir isotherm. The CH/Zn@H3BTC composite revealed outstanding adsorption on the metal interface as established by MD simulations and DFT calculations. Consequently, we found that the designed CH/Zn@H3BTC composite shows potential as an applicant inhibitor for steel protection.

NiCo LDH in situ derived NiCoP 3D nanoflowers coupled with a Cu3P p-n heterojunction for efficient hydrogen evolution

With the extensive consumption of non-renewable energy sources, storing solar energy as chemical energy has aroused people's wide concern. In this study, we successfully developed a novel Cu₃P@NiCoP composite photocatalyst to produce hydrogen by splitting water under visible light irradiation. Both the building of a p-n heterojunction between Cu₃P and NiCoP and the three-dimensional nanoflower structure of NiCoP play a vital role in improving the performance of the catalyst. On the one hand, the coupling of Cu₃P and NiCoP built a p-n heterojunction at the photocatalyst interface, and the heterojunction could promote the separation efficiency of photogenerated carriers and prolong the life span of charges, therefore enhancing the photocatalytic hydrogen production activity. On the other hand, the excellent catalytic performance of the photocatalyst was benefited by the flower-like microsphere structure of NiCoP, which could provide abundant active sites and a large specific surface area, and promote the adsorption of protons by the photocatalyst. Besides, the phosphating degree of the precursors and the ratio of Cu₃P and NiCoP were adjusted to get the best photocatalyst for hydrogen production, and the H₂ production of the optimal catalyst could reach 8897.44 μmol h^-1 g^-1. This work provides a new understanding for the rational design of heterojunction photocatalysts for outstanding hydrogen production performance.

Unique ternary Ni-MOF-74/Ni2P/MoSx composite for efficient photocatalytic hydrogen production: Role of Ni2P for accelerating separation of photogenerated carriers

A reasonable introduction of MOFs-derived Ni₂P with high dispersity is a valid way to reduce the recombination rate of photogenerated electron-holes, thus for more effective visible-light-driven water splitting. In this study, Ni-MOF-74/Ni₂P precursor was obtained by low-temperature phosphating method. A ternary heterojunction Ni-MOF-74/Ni₂P/MoS_x with a unique structure is obtained by a solution-based mixing method. The unique structure of Ni-MOF-74/Ni₂P provides advantages for MoS_x load. The UV-visible diffuse reflectance spectroscopy proves that the introduction of Ni₂P improves the utilization of visible light by the composite catalyst 10%-NPMS and promotes more electrons generation, thereby improving photocatalytic hydrogen production activity. It is proved that the introduced Ni₂P can accelerate the separation of photogenerated carriers by characterization (PL, EIS, LSV, etc.) analyses. The composite catalyst 10%-NPMS with the best hydrogen production activity was obtained by adjusting the ratio between Ni-MOF-74/Ni₂P and MoS_x. The photocatalytic hydrogen evolution of the composite catalyst 10%-NPMS (286.16 μmol) is 28.30, 2.78, 3.79 and 2.41 times that of pure Ni-MOF-74, Ni₂P, MoS_x and binary 10%-Ni-MOF-74/MoS_x within 5 h, respectively. And the hybrid 10%-Ni-MOF-74/Ni₂P/MoS_x exhibits excellent photocatalytic hydrogen evolution performance and good stability. This research will provide a new strategy for synthesizing unique ternary composite materials by using metal organic framework materials as precursors.

Synthesis of MOFs/GO composite for corrosion resistance application on carbon steel

Two unreported metal-organic frameworks [Cu(6-Me-2,3-pydc)(1,10-phen)·7H2O] n (namely Cu-MOF) and [Mn2(2,2'-bca)2(H2O)2] n (namely Mn-MOF) were synthesized by a solvothermal method and their structures were characterized and confirmed by elemental analysis, X-ray single crystal diffraction, Fourier infrared spectroscopy and thermogravimetric analysis. Cu-MOF/graphene (Cu-MOF/GR), Cu-MOF/graphene oxide (Cu-MOF/GO), Mn-MOF/graphene (Mn-MOF/GR) and Mn-MOF/graphene oxide (Mn-MOF/GO) composite materials were successfully synthesized by a solvothermal method and characterized and analyzed by PXRD, SEM and TEM. In order to study the corrosion inhibition properties of the Cu-MOF/GR, Cu-MOF/GO, Mn-MOF/GR and Mn-MOF/GO composite materials on carbon steel, they were mixed with waterborne acrylic varnish to prepare a series of composite coatings to explore in 3.5 wt% NaCl solution by electrochemical measurements and results showed that the total polarization resistance of the 3% Cu-MOF/GO and 3% Mn-MOF/GO composite coatings on the carbon steel surface were relatively large, and were 55 097 and 55 729 Ω cm2, respectively, which could effectively protect the carbon steel from corrosion. After immersion for 30 days, the 3% Mn-MOF/GO composite still maintained high corrosion resistance, the |Z| values were still as high as 23 804 Ω cm2. Therefore, MOFs compounded with GO can produce a synergistic corrosion inhibition effect and improve the corrosion resistance of the coating; this conclusion is well confirmed by the adhesion capability test.

Functionalized metal-organic frameworks for photocatalytic degradation of organic pollutants in environment

Currently, many kinds of organic pollutants in air and water have a negative impact on humans and the environment. Notably, as a type of new functional materials, metal-organic frameworks (MOFs) with well-ordered porous structures and numerous active sites have been proven to be ideal photocatalysts for the degradation of organic pollutants. In the past few years, many encouraging achievements have been made in the research field of MOFs for photocatalysis. And a large number of functionalized MOFs have been constructed to improve photocatalytic activity. In this review, recent progress in the photocatalytic degradation of organic pollutants in both air and water using functionalized MOFs are summarized in detail. The focus is on photocatalytic mechanisms and some strategies employed to achieve higher degradation efficiency. Furthermore, the challenges and outlooks in this promising filed are also discussed. We hope this review would be useful for designing more functionalized MOFs with greater photocatalytic performance for the degradation of organic pollutants in the environment.

WP modified S-scheme Zn0.5Cd0.5S/WO3 for efficient photocatalytic hydrogen production

In this work, a noble metal free photocatalyst WP/Zn_0.5Cd_0.5S/WO₃ (WZP) was prepared for the first time by simple hydrothermal and physical mixing methods.