Search Results (104)

This study addresses the challenges posed by weakly cemented strata in mine tunnels, where surrounding rock softens and deforms upon water exposure, which promotes the development of seepage pathways, and exhibits insufficient stability in bolt (cable) support systems. This study conducts laboratory grouting tests using silica sol on typical weakly cemented sandstone from Xinjiang mining areas. The mineral composition and pore structure were characterized using XRD, SEM, and mercury porosimetry. The injectable mixing ratio parameters for silica sol and the catalyst were determined through viscosity-time evolution tests. Grouting was performed using a custom-built constant-pressure grouting apparatus. After curing, unconfined compressive strength (UCS) and porosity-permeability tests were conducted to evaluate the micro-mechanism of grouting effects on the mechanical and permeability properties of weakly cemented sandstone. The results indicate: (1) The sandstone exhibits a high clay mineral content of 39.8%, dominated by illite. Its pores are primarily small-scale (10–100 nm), accounting for 79.31% of the total pore volume. This scale matches that of silica sol nanoparticles (approximately 9–20 nm), facilitating slurry penetration into micro-pores; (2) microscopic analyses reveal that silica sol effectively reconstructs pore structures through permeation filling and surface coating. Compared to KCl-induced gelation (with approximately 8% gel coverage), NaCl-induced gelation forms a more continuous gel film with more complete pore filling, achieving coverage of around 22%. Furthermore, the larger surface area of the gel aggregates indicates a more thorough filling of micro- and nano-pores, effectively enhancing rock mass compactness. (3) Permeability decreased from 6.91 mD to 3.55 mD, a reduction of 48.6%, while porosity decreased from 16.94% to 13.55%, showing a phased reduction during the grouting process; (4) following pressure grouting stabilization, the uniaxial compressive strength of sandstone increased appropriately by approximately 7–14%, while the elastic modulus rose by about 18–28%. The failure mechanism shifted from shear brittleness to a shear-tension composite state, with enhanced post-peak bearing capacity. These findings provide support for optimizing silica sol grouting parameters in weakly cemented strata tunnels and for the synergistic reinforcement of rock mass permeability and strength. Full article

High-entropy alloys (HEAs) exhibit excellent catalytic activity owing to their unique structure and chemical properties. The construction of hierarchical porous HEA catalysts via laser powder bed fusion (LPBF, a typical 3D printing technology) and dealloying techniques opens new avenues for boosting catalytic performance. This study reports the fabrication of a hierarchical porous FeCoNiCuAl HEA catalyst through a two-step strategy: LPBF and subsequent dealloying. The macroscopic triply periodic minimal surface (TPMS) structure of the HEA catalyst was constructed through LPBF, followed by dealloying to create a nanoporous structure on the catalyst surface. The hierarchical porous FeCoNiCuAl HEA catalyst exhibited a catalytic activity 4.33 times higher than that of the pristine, non-porous FeCoNiCuAl HEA (HEA-0). Furthermore, the catalyst maintained nearly 100% degradation efficiency for Acid Red G (ARG) after 20 consecutive catalytic cycles, demonstrating exceptional stability. This stepwise strategy for constructing hierarchical porous structures not only accelerates mass transfer via the macroporous framework but also significantly increases the density of accessible active sites through the nanoporous surface, thereby synergistically enhancing the catalytic activity of HEAs. This work provides a novel and scalable approach for developing high-performance porous HEA catalysts for wastewater treatment. Full article

p-Nitrophenol (PNP), a highly toxic and recalcitrant organic pollutant prevalent in industrial wastewater, poses severe challenges to traditional Fenton treatment technologies. In this study, a novel nanoporous catalyst is synthesized via a combined annealing–dealloying strategy. Annealing at 550 °C and 600 °C induces partial crystallization, generating α-Fe and Fe₂B phases that serve as preferential corrosion sites during chemical dealloying. This process results in a three-dimensionally interconnected nanoporous structure, which significantly increases the specific surface area of the catalyst to 2.642 m²/g. The optimized nanoporous catalyst exhibits excellent degradation performance, achieving complete removal of PNP within 30 min under room temperature reaction conditions. Notably, kinetic analysis reveals a degradation mechanism involving adsorption and Fenton-like catalysis. The high specific surface area provides abundant active sites for PNP adsorption, while the enhanced Fe²⁺ dissolution synergistically accelerates the degradation. The adsorption kinetic follows a pseudo-second-order model, and the degradation kinetic conforms to a first-order model, with activation energy analysis further confirming a surface-reaction-controlled process. This work provides a feasible approach and technical reference for designing efficient porous catalysts based on amorphous alloys for advanced treatment of refractory organic wastewater. Full article

Pt-rare earth metal (Pt-RE) alloys are considered to be one of the most promising electrocatalysts for producing oxygen reduction reactions (ORRs) due to their compressively strained Pt overlayer and their exceptional negative-alloy formation energies, which result in excellent activity and stability. However, there are still great challenges in the chemical synthesis of Pt-RE nanoalloys. Herein, we report a simple method employing the nanopores of porous carbon as nanoreactors to synthesize a Pt₅La nanoalloy. The Pt₅La alloy nanoparticles are embedded in porous carbon (Pt₅La@C) with a particle size of around 1–3 nm and also exhibit a very narrow size distribution because of the confined-space effect. The as-prepared Pt₅La@C nanoalloy exhibits highly efficient ORR performance with a half-wave potential of 0.912 V in 0.1 M HClO₄, which is 56 mV higher than that of a commercial Pt/C catalyst. Moreover, it achieves an improved intrinsic activity of 0.69 mA cm⁻² and, a mass activity of 0.42 A mg_Pt⁻¹ at 0.90 V. In addition, it also delivers a very stable lifespan performance, with negligible decay in half-wave potential after accelerated stress testing for 10,000 cycles. This work also provides a new method for the development of promising Pt-RE nanoalloys with ultrasmall nanoparticles with a very narrow size distribution for various efficient energy-conversion devices. Full article

Silicon carbide (SiC) has attracted increasing attention as a robust photoelectrode material for solar water splitting due to its exceptional chemical stability, mechanical strength, and resistance to photocorrosion. Recent advances in nanostructuring—particularly the development of nanoporous SiC architectures—have dramatically improved light absorption, charge separation, and charge transport in this material. This review summarizes current strategies to enhance the PEC performance of SiC, including hierarchical nanostructuring, defect engineering (e.g., doping to tailor band structure), heterojunction formation with co-catalysts, and incorporation of plasmonic nanoparticles. Remaining challenges are discussed, notably the wide band gap of common SiC polytypes (limiting visible-light utilization) and rapid charge-carrier recombination. In addition, we examine the techno-economic prospects for SiC-based PEC systems, outlining the efficiency and durability benchmarks required for commercial hydrogen production. Finally, we propose future research directions to achieve efficient, durable SiC photoelectrodes and to guide the development of scalable PEC water-splitting devices. This review uniquely integrates material design strategies with techno-economic evaluation, providing a roadmap for SiC-based PEC systems. Full article

Electrocatalytic water splitting for hydrogen production is a crucial technology in achieving carbon neutrality. The development of efficient and stable hydrogen evolution reaction (HER) electrocatalysts is a core challenge in this field. This review systematically summarizes the latest research advancements in nanoporous transition metal-based catalysts, covering metal alloys and compounds. Through strategies such as compositional optimization, crystal structure modulation, interface engineering, and nanoporous structure design, these non-precious metal catalysts exhibit outstanding performance comparable to commercial platinum-carbon catalysts across a wide pH range. This paper thoroughly discusses the catalytic mechanisms of different material systems, including electronic structure regulation, active site exposure, and mass transport optimization. Finally, the challenges faced in current research are summarized, and future directions are projected, including scalable fabrication processes and performance validation in real electrolysis cell environments. This review provides significant insights into designing next-generation efficient and stable non-precious metal electrocatalysts. Full article

Herein, we prepared nanoparticles of chitosan–manganese(II) complexes in different molar ratios (1:2, 1:1, and 2:1) and fully characterized them using dynamic and electrophoretic light scattering, X-ray diffraction, SEM, FTIR, and thermal analysis. Nanoparticles Chitosan + Mn²⁺ (1:1) have a high catalytic activity in the oxidative coupling of benzylamine, resulting in the imine formation and also in selective aldol reaction. Chitosan + Mn²⁺ (1:1) catalyze the reactions in the greenest solvents: water and water/ethanol mixture. Moreover, Chitosan + Mn²⁺ (1:1) is very easy to prepare and convenient to use. The catalyst is separated from the reaction mixture by a simple nanoporous filter or centrifugation and does not lose catalytic activity after at least ten uses. The chitosan–manganese(II) complexes reduce the milk fermentation time, demonstrating the effectiveness in accelerating the fermentation process by Streptococcus thermophilus. They also contribute to increasing the shelf life of fermented milk products by inhibiting the undesirable post-acidification process. We found that the optimal ratio of chitosan and Mn²⁺ to manifest the apogee of the desired effects (acceleration of milk fermentation and increase in the shelf life of the fermented product) is 1:2. Full article

Methodological fusion of materials chemistry, which enables us to create materials, with nanotechnology, which enables us to control nanostructures, could enable us to create advanced functional materials with well controlled nanostructures. Positioned as a post-nanotechnology concept, nanoarchitectonics will enable this purpose. This review paper highlights the broad scope of applications of the new concept of nanoarchitectonics, selecting and discussing recent papers that contain the term ‘nanoarchitectonics’ in their titles. Topics include controls of dopant atoms in solid electrolytes, transforming the framework of carbon materials, single-atom catalysts, nanorobots and microrobots, functional nanoparticles, nanotubular materials, 2D-organic nanosheets and MXene nanosheets, nanosheet assemblies, nitrogen-doped carbon, nanoporous and mesoporous materials, nanozymes, polymeric materials, covalent organic frameworks, vesicle structures from synthetic polymers, chirality- and topology-controlled structures, chiral helices, Langmuir monolayers, LB films, LbL assembly, nanocellulose, DNA, peptides bacterial cell components, biomimetic nanoparticles, lipid membranes of protocells, organization of living cells, and the encapsulation of living cells with exogenous substances. Not limited to these examples selected in this review article, the concept of nanoarchitectonics is applicable to diverse materials systems. Nanoarchitectonics represents a conceptual framework for creating materials at all levels and can be likened to a method for everything in materials science. Developing technology that can universally create materials with unexpected functions could represent the final frontier of materials science. Nanoarchitectonics will play a significant part in achieving this final frontier in materials science. Full article

Nanoporous Pt/C electrodes fabricated via aerosol coating offer excellent reactant delivery and electrochemical activity owing to their high porosity. However, the practical application prospects of such electrodes are limited by their poor mechanical properties. Herein, we quantitatively analyze the effects of thermal annealing (at 110, 150, 190, and 230 °C) on the mechanical stability and electrical properties of aerosol-based Pt/C electrodes. Post-annealing at an optimal temperature of 190 °C improved the tensile strength by 65.3%, increased their elongation from 0.82% to 1.78%, and decreased the electrical resistance while maintaining the secondary pore structure. Analyses of the electrode’s surface roughness, pore structure, and contact angle indicate that thermal reconstruction of the ionomer is crucial for stabilizing the electrode structure and controlling its surface properties. Finite element simulations using experimentally measured single-electrode properties enabled accurate prediction of the mechanical behavior of the membrane electrode assembly. These results provide design guidelines for balancing the process efficiency with the mechanical stability of aerosol-based Pt/C electrodes and can be used to improve their application prospects in aerosol-based fuel cell catalyst layers. Full article

Dealloying technique has been used for centuries as an attractive method for producing porous surfaces by removing one or more undesirable elements from the surface. Since early 2000s, the technique has been further developed for understanding the dealloying mechanism and tailoring it to produce chemically homogeneous materials with nanoporous (np) morphology. Dealloying has found numerous applications such as sensors, catalysts, as well as in the biomedical field, which is fairly recent and has attracted great attention on this topic. This review investigates the dealloying technique for preparing nanoporous materials and nanoporous surfaces by using different modification routes on various types of Ti-based alloys for biomedical implant application. There has been significant growth in studying dealloying of crystalline, amorphous, shape memory, and composites-based Ti alloys. This review aims to summarise the findings from literature and discuss the scope of this technique and challenges involved for future aspects. Full article

A major challenge for Li-O₂ batteries is the slow kinetics of oxygen reduction (ORR) and evolution (OER) reactions. This work presents a high-performance Pt₃Rh/C composite cathode where Pt-Rh nanoalloys are uniformly dispersed on 3D nanoporous carbon. The bimetallic architecture demonstrates significantly enhanced ORR/OER activity compared to conventional catalysts. Super P, with a large specific surface area and omnipresent pores with diverse size distribution, provided sufficient storage space for Li₂O₂ and facilitated transport channels for Li⁺ and O₂, while the highly conductive Pt₃Rh NPs optimized catalytic efficiency. XPS reveals a prominent electron transfer process between Pt and Rh; the Rh sites in Pt₃Rh/C alloy can effectively act as electron donors to improve the oxygen/lithium peroxide (O₂/Li₂O₂) redox chemistry in LOB. Therefore, the Pt₃Rh/C electrode shows the minimum overpotential (0.60 V) for efficient oxygen reduction and evolution under an upper-limit capacity of 2000 mAh g⁻¹. This work introduces a Pt₃Rh/C nanoalloy synthesis method that boosts Li-O₂ battery efficiency by accelerating oxygen reaction kinetics. Full article

As an efficient clean energy technology, water electrolysis for hydrogen production has its efficiency limited by the sluggish oxygen evolution reaction (OER) kinetics, which drives the demand for the development of high-performance anode OER catalysts. This work constructs bimetallic (Al, Mn) co-doped nanoporous spinel CoFe₂O₄ (np-CFO) with a tunable structure and composition as an OER catalyst through a simple two-step dealloying strategy. The as-formed np-CFO (Al and Mn) features a hierarchical flaky configuration; that is, there are a large number of fine nanosheets attached to the surface of a regular micron-sized flake, which not only increases the number of active sites but also enhances mass transport efficiency. Consequently, the optimized catalyst exhibits a low OER overpotential of only 320 mV at a current density of 10 mA cm⁻², a minimal Tafel slope of 45.09 mV dec⁻¹, and exceptional durability. Even under industrial conditions (6 M KOH, 60 °C), it only needs 1.83 V to achieve a current density of 500 mA cm⁻² and can maintain good stability for approximately 100 h at this high current density. Theoretical simulations indicate that Al and Mn co-doping could indeed optimize the electronic structure of CFO and thus decrease the energy barrier of OER to 1.35 eV. This work offers a practical approach towards synthesizing efficient and stable OER catalysts. Full article

The sludge produced by the Fenton process contains mixed-valence iron particulates (hereafter called Fenton wastes). Using a solvothermal method, we fabricated a new heterogeneous photo-Fenton catalyst using Fenton wastes and metal–organic frameworks (MOFs). Nanoporous metal carboxylate (MIL-88) MOF impregnated with Fenton waste was functionalized using 2,5-dihydroxyterephthalic acid (x-HO-MIL-88-C, x, concentration of the 2,5-dihydroxyterephthalic acid). The efficiency of x-HO-MIL-88-C was examined under visible light radiation using methylene blue (MB) as an index pollutant. We observed the best catalytic performance for MB degradation by 4-HO-MIL-88-C. In the photo-Fenton process, the simultaneous presence of singlet oxygen, superoxide, and hydroxyl radicals is confirmed by free radical quenching and electron spin resonance spectral data. These free radicals associate with holes in the non-selective degradation of MB. The 4-HO-MIL-88-C catalyst shows good stability and reusability, maintaining over 80% efficiency at the end of five consecutive cycles. This work opens up a new path for recycling Fenton wastes into usable products. Full article

Advanced oxidation processes offer bright potential for eliminating organic pollutants from wastewater, where the development of efficient catalysts revolves around deep understanding of the microstructure–property–performance relationship. In this study, we explore how microstructural engineering influences the catalytic performance of nanoporous copper (NPC) in degrading organic contaminants. By systematically tailoring the NPC microstructure, we achieve tunable three-dimensional porous architectures with nanoscale pores and macroscopic grains. This results in a homogeneous, bicontinuous pore–ligament network that is crucial for the oxidative degradation of the model pollutant methylene blue in the presence of hydrogen peroxide. The catalytic efficiency is assessed using ultraviolet–visible spectroscopy, which reveals first-order degradation kinetics with a rate constant κ = 44 × 10⁻³ min⁻¹, a 30-fold improvement over bulk copper foil, and a fourfold increase over copper nanoparticles. The superior performance is attributed to the high surface area, abundant active sites, and multiscale porosity of NPC. Additionally, the high step-edge density, nanoscale curvature, and enhanced crystallinity contribute to the catalyst’s remarkable stability and reactivity. This study not only provides insights into microstructure–property–performance relationships in nanoporous catalysts but also offers an effective strategy for designing efficient and scalable materials for wastewater treatment and environmental applications. Full article

Electrochemical nitrogen reduction reaction (NRR) has emerged as a promising approach for sustainable ammonia synthesis under ambient conditions, offering a low-energy alternative to the traditional Haber–Bosch process. However, the development of efficient and sustainable electrocatalysts for NRR remains a significant challenge. Noble metals, known for their exceptional chemical stability under electrocatalytic conditions, have garnered considerable attention in this field. In this study, we report the successful synthesis of nanoporous CuAuPtPd quasi-high-entropy alloy (quasi-HEA) prism arrays through “melt quenching” and “dealloying” techniques. The as-obtained alloy demonstrates remarkable performance as an NRR electrocatalyst, achieving an impressive ammonia synthesis rate of 17.5 μg h⁻¹ mg⁻¹ at a potential of −0.2 V vs. RHE, surpassing many previously reported NRR catalysts. This work not only highlights the potential of quasi-HEAs as advanced NRR electrocatalysts but also provides valuable insights into the design of nanoporous multicomponent materials for sustainable energy and catalytic applications. Full article