Rational Design of Inhibitor-Encapsulated Bio-MOF-1 for Dual Corrosion Protection.

Searching for the efficient and sustainable inhibitors to defend metal corrosion in the marine environment has received a great deal attention in both academia and industry. In this work, a new strategy was developed to encapsulate benzimidazole (BI) inhibitor guest molecules into the micropores of bio-MOF-1, which was constructed with the other natural adenine inhibitor. Electrochemical characterizations revealed that the slowly sustained release of BI and adenine inhibitors from the BI@bio-MOF-1 composite presented excellent anti-corrosion durability in the whole mild steel corrosion process. The impedance arc value attained approximately 5000 Ω·cm2 at initially 2 h and further increased to 6000 Ω·cm2 after 5 days immersion in 0.5 M NaCl solution, and the inhibition efficiency reached 85.36% due to the synergistic dual inhibitive effect of BI@bio-MOF-1 composite. The dual inhibition-based bio-MOF-1 composite equipped strong metal-chelating capability and response durability, exhibiting high potentiality for metal anti-corrosion applications.

In†Situ Electrochemical Synthesis of Oriented and Defect-Free AEL Molecular-Sieve Films Using Ionic Liquids.

Simply preparing oriented and defect-free molecular-sieve films have been a long-standing challenge both in academia and industry. Most of the early works focus on the careful and multiple controls of the seeds layer or synthesis conditions. Herein, we report a one-step in situ electrochemical ionothermal method that combines a controllable electric field with ionic liquids. We demonstrate that an in-plane oriented and defect-free AEL (one molecular-sieve framework type) molecular-sieve film was obtained using an Al electrode as the Al source. The excellent corrosion-resistant performance of the film makes this technology promising in multiple applications, such as anti-corrosion coatings.

Zeolite-Templated Carbons Supported Rh and Ru Electrocatalysts for Highly Active Hydrogen Evolution Reaction.

Here, we report the systematical synthesis of zeolite-templated carbon (ZTC) supported Ru and Rh mono- or bi-metallic electrocatalysts towards hydrogen evolution reaction (HER). The zeolite A or ZSM-5 derived ZTC supports and metal sites were adjusted, and all electrocatalysts outperformed the commercial Pt/C electrocatalyst for HER performance. In particular, the RhRu/(ZTC/ZSM5) sample exhibited superior catalytic performance with the overpotential of 24.8 mV@10 mA ⋅ cm-2, and outstanding stability with 1 mV drop after 20000 cyclic voltammetry circles. This work offers a simple impregnation method for the synthesis of highly performed HER electrocatalysts supported on porous zeolite-templated carbon.

Free-Standing Metal-Organic Framework Membranes Made by Solvent-Free Space-Confined Conversion for Efficient H2/CO2 Separation.

Metal-organic frameworks (MOFs) are promising candidates for the advanced membrane materials based on their diverse structures, modifiable pore environment, precise pore sizes, etc. Nevertheless, the use of supports and large amounts of solvents in traditional solvothermal synthesis of MOF membranes is considered inefficient, costly, and environmentally problematic, coupled with challenges in their scalable manufacturing. In this work, we report a solvent-free space-confined conversion (SFSC) approach for the fabrication of a series of free-standing MOF (ZIF-8, Zn(EtIm)2, and Zn2(BIm)4) membranes. This approach excludes the employment of solvents and supports that require tedious pretreatment and, thus, makes the process more environment-friendly and highly efficient. The free-standing membranes feature a robust and unique architecture, which comprise dense surface layers and highly porous interlayer with large amounts of irregular-shaped micron-scale pore cavities, inducing satisfactory H2/CO2 selectivities and exceptional H2 permeances. The ZIF-8 membrane affords a considerable H2 permeance of 2653.7 GPU with a competitive H2/CO2 selectivity of 17.1, and the Zn(EtIm)2 membrane exhibits a high H2/CO2 selectivity of 22.1 with an excellent H2 permeance (6268.7 GPU). The SFSC approach potentially provides a new pathway for preparing free-standing MOF membranes under solvent-free conditions, rendering it feasible for scale-up production of membrane materials for gas separation.

New TiO2 -Based Oxide for Catalyzing Alkaline Hydrogen Evolution Reaction with Noble Metal-Like Performance.

The development of cost-effective electrocatalysts with high activity and sufficient stability for hydrogen evolution reaction (HER) is crucial for the widespread application of water electrolysis for sustainable H2 production. Transition metal oxides are desirable alternatives to replace benchmark Pt-based HER electrocatalysts because of their cost effectiveness, facile synthesis, versatile compositions, and easy electronic structure tuning. However, most available transition metal oxides show poor performance for HER catalysis. Here, it is reported that the anatase TiO2 can be efficiently developed into a superior HER electrocatalyst with comparable activity to Pt-based electrocatalysts in alkaline solution through simultaneous morphology control, proper lattice doping, and surface active sites engineering. Specifically, the obtained cobalt-doped TiO2 nanorod arrays (Co-TiO2 @Ti(H2 )) show a low overpotential of only 78 mV at 10 mA cm-2 , a small Tafel plot of 67.8 mV dec-1 , and excellent stability even at an ultralarge current density of ≈480 mA cm-2 in 1.0 m KOH solution. Theoretical calculations demonstrate that the introduction of Co with rich oxygen vacancies can efficiently lower the energy barrier for water adsorption/dissociation and H intermediate desorption. This work uncovers the potential of the low-cost transition metal oxides as alternative HER electrocatalysts in alkaline water electrolysis.

Fe3O4@N-Doped Interconnected Hierarchical Porous Carbon and Its 3D Integrated Electrode for Oxygen Reduction in Acidic Media.

The rational design of electrode structure with catalysts adequately utilized is of vital importance for future fuel cells. Herein, a novel 3D oriented wholly integrated electrode comprising core-shell Fe3O4@N-doped-C (Fe3O4@NC) nanoparticles embedded into N-doped ordered interconnected hierarchical porous carbon (denoted as Fe3O4@NC/NHPC) is developed for the oxygen reduction reaction (ORR). The as-prepared catalyst possesses novel structure and efficient active sites. In rotating disk electrode measurements, the Fe3O4@NC/NHPC exhibits almost identical ORR electrocatalytic activity, superior durability, and much better methanol tolerance compared with the commercial Pt/C in acidic media. To the authors' knowledge, this is among the best non-precious-metal ORR catalysts reported so far. Importantly, the Fe3O4@NC/NHPC is successfully in situ assembled onto carbon paper by the electrophoresis method to obtain a well-designed 3D-ordered electrode. With improved mass transfer and maximized active sites for ORR, the 3D-oriented wholly integrated electrode shows superior performance to the one fabricated by the traditional method.

Insights into Correlation among Surface-Structure-Activity of Cobalt-Derived Pre-Catalyst for Oxygen Evolution Reaction.

Rational design of unique pre-catalysts for highly active catalysts toward catalyzing the oxygen evolution reaction (OER) is a great challenge. Herein, a Co-derived pre-catalyst that allows gradual exposure of CoOOH that acts as the active center for OER catalysis is obtained by both phosphate ion surface functionalization and Mo inner doping. The obtained catalyst reveals an excellent OER activity with a low overpotential of 265 mV at a current density of 10 mA cm-2 and good durability in alkaline electrolyte, which is comparable to the majority of Co-based OER catalysts. Specifically, the surface functionalization produces lots of Co-PO4 species with oxygen vacancies which can trigger the surface self-reconstruction of pre-catalyst for a favorable OER reaction. Density functional theory calculations reveal that the Mo doping optimizes adsorption-free energy of *OOH formation and thus accelerates intrinsic electrocatalytic activity. Expanding on these explorations, a series of transition metal oxide pre-catalysts are obtained using this general design strategy. The work offers a fundamental understanding toward the correlation among surface-structure-activity for the pre-catalyst design.

In situ surface reconstruction synthesis of a nickel oxide/nickel heterostructural film for efficient hydrogen evolution reaction.

A simple method is provided to achieve in situ surface reconstruction synthesis of a heterostructural NiO/Ni film on carbon cloth (NiO/Ni@CC) for the hydrogen evolution reaction (HER). This ultrafast reconstruction process brings a hydrophilic surface and abundant heterostructures with rich oxygen vacancies exhibiting a low HER overpotential and remarkable stability.

Insights into the interplay between electric fields and microstructures of AEL films under ionothermal conditions.

A facile method for precise microstructure control of molecular sieve films remains a great challenge. In contrast to conventional hydrothermal methods, herein AEL molecular sieve films with preferred c-orientation are in situ fabricated through elaborate programming of the applied electric fields under ionothermal conditions. The approach developed here may pave a new avenue for designing and fabricating high quality molecular sieve films with diverse microstructures and functionality.