Natural Wood-Based Catalytic Membrane Microreactors for Continuous Hydrogen Generation

Autonomous humidity regulation by MOF/wood composites

Maintaining indoor air relative humidity (R.H.) within the 40-60% range recommended by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) significantly impacts human comfort and health. However, conventional solutions like dehumidifiers and humidifiers increase energy consumption, challenging the building sector's carbon neutrality goals. Here, we present an innovative composite material comprising wood and metal-organic frameworks (MOFs) that passively regulates indoor humidity by absorbing and releasing moisture. Our universal fabrication strategy enhances wood scaffold accessibility and increases MOF loading, resulting in a significant surface area increase, surpassing previous MOF/wood composites. This MOF/wood composite exhibits remarkable water sorption capacity, autonomously maintaining indoor humidity around 45% R.H. without external energy consumption. This aligns with ASHRAE recommendations, offering indirect energy savings and promoting a health-friendly indoor environment. Furthermore, the MOF/wood composite outperforms many existing materials in mechanical strength, dimensional stability, and scalability, making it highly suitable for building applications and contributing to carbon neutrality in the building sector.

Recent Advances and Perspectives on Supported Catalysts for Heterogeneous Hydrogen Production from Ammonia Borane

Ammonia borane (AB), a liquid hydrogen storage material, has attracted increasing attention for hydrogen utilization because of its high hydrogen content. However, the slow kinetics of AB hydrolysis and the indefinite catalytic mechanism remain significant problems for its large-scale practical application. Thus, the development of efficient AB hydrolysis catalysts and the determination of their catalytic mechanisms are significant and urgent. A summary of the preparation process and structural characteristics of various supported catalysts is presented in this paper, including graphite, metal-organic frameworks (MOFs), metal oxides, carbon nitride (CN), molybdenum carbide (MoC), carbon nanotubes (CNTs), boron nitride (h-BN), zeolites, carbon dots (CDs), and metal carbide and nitride (MXene). In addition, the relationship between the electronic structure and catalytic performance is discussed to ascertain the actual active sites in the catalytic process. The mechanism of AB hydrolysis catalysis is systematically discussed, and possible catalytic paths are summarized to provide theoretical considerations for the designing of efficient AB hydrolysis catalysts. Furthermore, three methods for stimulating AB from dehydrogenation by-products and the design of possible hydrogen product-regeneration systems are summarized. Finally, the remaining challenges and future research directions for the effective development of AB catalysts are discussed.

Gravity-driven rattan-based catalytic filter for rapid and highly efficient organic pollutant removal

Metal organic frameworks hold great promise as heterogeneous catalysts in sulfate radical (SO₄^∙-) based advanced oxidation. However, the aggregation of powdered MOF crystals and the complicated recovery procedure largely hinder their large-scale practical applications. It is important to develop eco-friendly and adaptable substrate-immobilized metal organic frameworks. Based on the hierarchical pore structure of the rattan, gravity-driven metal organic frameworks loaded rattan-based catalytic filter was designed to degrade organic pollutants by activating PMS at high liquid fluxes. Inspired by the water transportation of rattan, ZIF-67 was in-situ grown uniformly on the rattan channels inner surface using the continuous flow method. The intrinsically aligned microchannels in the vascular bundles of rattan acted as reaction compartments for the immobilization and stabilization of ZIF-67. Furthermore, the rattan-based catalytic filter exhibited excellent gravity-driven catalytic activity (up to 100 % treatment efficiency for a water flux of 10173.6 L·m^-2·h^-1), recyclability, and stability of organic pollutant degradation. After ten cycles, the TOC removal of ZIF-67@rattan was 69.34 %, maintaining a stable mineralisation capacity for pollutants. The inhibitory effect of the micro-channel promoted the interaction between active groups and contaminants, increasing the degradation efficiency and improving the stability of the composite. The design of a gravity-driven rattan-based catalytic filter for wastewater treatment provides an effective strategy for developing renewable and continuous catalytic systems.

Carbonized wood impregnated with bimetallic nanoparticles as a monolithic continuous-flow microreactor for the reduction of 4-nitrophenol

Porous monolithic microreactors show great promise in catalytic applications, but are usually based on non-renewable materials. Herein, we demonstrate a Ni/Au nanoparticle-decorated carbonized wood (Ni/Au-CW) monolithic membrane microreactor for the efficient reduction of 4-nitrophenol. The hierarchical porous wood structure supports uniformly distributed heterobimetallic Ni/Au nanoparticles. As a consequence of these two factors, both mass diffusion and electron transfer are enhanced, resulting in a superior reduction efficiency of 99.5% as the liquor flows through the optimised Ni/Au-CW membrane. The reaction mechanism was investigated by electron paramagnetic resonance spectroscopy and density functional theory calculations. The proposed attraction-repulsion mechanism facilitated by the bimetallic nanoparticles has been ascribed to the different electronegativities of Ni and Au. The Ni/Au-CW membrane exhibits excellent catalytic performance and could be applicable to other catalytic transformations.

Review of Wood Modification and Wood Functionalization Technologies

Wood modifications are becoming popular as a way to enhance the performance of wood, either to make it more durable, improve the performance of wood, or give it new functionality as a multifunctional or smart material. While wood modifications have been examined since the early 1900s, the topic has become a dominant area of study in wood science over the past decade. This review summarizes recent advances and provides future perspective on a selection of wood modifications, i.e., the methods that are currently commercialized (acetylation, furfurylation, and thermal modification), a rediscovered ancient practice (charring), a family of polymerization modifications that have so far made it to the pilot scale, and examples of novel wood-based functional materials explored at laboratory scale.