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This paper focuses on the particle crushing mechanism of construction solid waste recycled aggregate (CWRA), particularly recycled concrete (RC) and recycled bricks (RB), using natural gravel (NG) as a control group. Compression tests, combined with the Weibull distribution, fractal dimension theory, and relative crushing rate, were conducted to investigate the crushing behavior of these materials under different loads. Results indicate that, under the same load, the crushing degree ranks from highest to lowest as RB, RC, and NG. The Weibull distribution effectively describes the crushing state, with “fragmentation” being the primary mode for most materials, while RC also exhibits “grinding.” As the load increases, the relative crushing rate rises for all materials but slows beyond a certain load threshold, indicating greater difficulty in further crushing. The study identifies a load threshold of 400 kN, beyond which changes in void fraction and relative crushing rates become less significant, particularly in stronger aggregates. HighlightsIdentified that mortar attached to the RC surface is the primary cause of the increased particle crushing below 0.6 mm.Introduced Weibull distribution parameters aand bto accurately characterize the crushing state of RA particles.Revealed the errors between fractal dimension-based evaluations and the actual crushing state of RC particles.Proposed a two-stage crushing mode for RC.Determined the critical threshold value for the variation of crushing degree with load level.

Acetone is a tracer for monitoring air quality and a potential breath maker for diabetes. It remains a great challenge for current portable sensors to sensitively and selectively detect acetone at low-ppb (part per billion) level. Herein, we present an ordered mesoporous nickel oxide (NiO) with both large mesopores and ultrathin crystalline frameworks for the detection of low-ppb acetone. The ordered mesoporous NiO replicas with predominant large mesopores of 11 nm, high specific surface areas of 121–128 m2/g and ultrathin crystalline frameworks of 5 nm were synthesized by the nanocasting method and the crystalline properties of NiO frameworks were adjusted by changing the annealing temperature from 300 °C to 750 °C, which resulted in different contents of oxygen deficient on the surface of ultrathin frameworks. The gas-sensing properties for all the NiO samples were investigated and the ordered large-pore mesoporous NiO (NiO-600) with maximum oxygen deficient obtained at 600 °C exhibited the highest response (Rgas/Rair−1=2.9) toward acetone (1 ppm, ppm: part per million), which is 3.4 and 30 times larger than those for common mesoporous NiO obtained at 300 °C and bulk NiO. Notably, a low detection limit (2 ppb), good selectivity and cycling stability were also observed in NiO-600.

Introducing oxygen vacancies in transition-metal oxides is an effective method to improve electrocatalytic water oxidation activity. However, controlled defect engineering in metal oxides remains a challenge. In this study, high oxygen vacancy content is achieved in transition-metal oxides by regulating the pyrolysis temperature of corresponding metal hydroxides. Specifically, Co3O4nanoflowers with a large amount of oxygen vacancies were obtained by pyrolysis of Co(OH)2in air at 400°C. The high oxygen vacancy content may be due to the rich porous structure and atomic rearrangement of Co and O. Electrochemical results showed that oxygen vacancy defect-rich Co3O4prepared at 400°C (Co3O4-400) has the lowest overpotential ηof 321 mV for oxygen evolution reaction at a current density jof 10 mA cm−2in 1.0 mol L−1KOH compared with Co3O4-300 (348 mV) and Co3O4-500 (366 mV). Theoretical calculations and experiments verified the beneficial effect of oxygen vacancies in Co3O4. This study offers an efficient strategy to develop highly active transition-metal oxides with optimized oxygen vacancies.

Aqueous zinc‐ion batteries (AZIB) are increasingly recognized as a promising next‐generation energy storage technology, prized for their affordability and high safety profile. Yet, their widespread adoption is challenged by complex reaction mechanisms and the evolving nature of both the electrode material and interfaces, which remain critical barriers. This review underscores the utility of in situ and operando characterization techniques in AZIB systems, offering invaluable tools for tracking these intricate processes and deepening understanding of energy storage mechanisms. This review presents an extensive overview of cutting‐edge in situ and operando methods, emphasizing their crucial role in structural investigations of materials and interfaces during electrochemical processes. This review particularly focuses on the synergistic application of various in situ techniques, delving into the nuances of experimental setups and data interpretation. Finally, it addresses current challenges in the field and proposes potential strategies, aiming to enhance the impact and broaden the application of these techniques for future advancements and mechanistic insights in AZIB research. The cutting‐edge in situ and operando methods is summarized and the crucial role in structural investigations of materials and interfaces during electrochemical processes is presented herein.

As the world’s largest energy consumer (i.e., 24% of the world) and one of the largest biomass resource reserve countries (i.e., total reserves of 73.42 × 108t a–1), for China, using biomass to prepare for biochar and store it in soil to realize the “carbon sequestration and emission reduction” is of great significance. This paper explores the physical–chemical properties of biochar and finds out its reason–manifestation–influencing factors for “carbon sequestration reduction”. A series of life cycle assessment calculation methods were introduced to biochar from China’s four main biomasses (i.e., crop straw, firewood and forest trees, livestock manure, and urban organic waste). According to the evaluation of “carbon sequestration function” and “emission reduction benefit”, the greenhouse gas emission reduction (i.e., CO2e, where CO2eis CO2equivalent) is 4.51 × 108, 2.66 × 108, 4.18 × 108, and 3.01 × 108t of CO2efor raw materials, respectively. The total potential of biochar to mitigate greenhouse gas emissions is 14.36 × 108t of CO2e, which is equivalent to 15.23% of China’s total greenhouse gas emissions. Through economic analysis of farmers and pyrolysis plants, it can be concluded that, when the carbon trading price is 300 CNY t–1of CO2e, it will result in an economic gap of 21.3 × 1010CNY a–1, which requires a certain subsidy from the government. For crop stalks, firewood, woods, and livestock manure biomass resources are 7200, 7000, and 2500 CNY hm–2a–1, respectively. If the carbon trading price can be increased to 600 CNY t–1of CO2e, both the farmers and the pyrolysis plant will have huge economic benefits. Finally, the existing bottlenecks of the technology are analyzed; the corresponding prospects are put forward; and the existing biomass utilization balance issues are discussed.

A good understanding of the catalytic mechanism of alkali and alkaline earth metal species during pyrolysis is required for the development of biomass utilization, to take advantage of its special thermochemical properties. The mechanism of the volatile–biochar interaction, especially between H radical/CO2/H2O and K/Ca in biochar, was systematically investigated by combining experimental analyses and density functional theory calculation. The results indicate that, at 500–900 °C, the yield of biochar from rice husk pyrolysis is basically constant, which mainly shows the mutual conversion between gas and liquid products. With the increase of loading alkali and alkaline earth metal species (AAEMs), the tar yield gradually decreased, and with it reaching a certain content, a significant catalytic effect of AAEMs can be observed. K is more beneficial to maintain the stability of the biochar structure than Ca. The intensities of C═O and C–O–C functional groups would appear with a certain increase with the increasing concentration of bond-linking AAEMs. At 700–900 °C, the precipitation ratio of K is almost twice that of Ca and even more. The presence of AAEMs can largely inhibit the formation of three-ring tar components, and more converted to one-ring tar components. The H radicals in the volatile can be bonded to C in the C–O–K structure, thereby causing the K element to decouple with the functional group, and tend to be adsorbed on the carbon matrix. For the Ca-loaded structure, it is manifested in strong adsorption of H radicals by Ca, resulting in the weakening of C–O bonds and the looseness of the biochar structure. The interaction between K/Ca in biochar and H2O/CO2is reflected in the mutual attraction of AAEMs and the O atom in the H2O/CO2molecule.

• Bimetal sulfides NiS 2 /MoS 2 with abundant exposed edge sites and electron transfer-favoring layered structure. • CFP served as a support to control the heterostructures of NiS 2 /MoS 2. • 3D hierarchical NiS 2 /MoS 2 nanostructures on CFP exhibit the overpotential of 102 mV (10 mA cm−2), a Tafel slope of 67 mV/dec and a high double-layer capacity of 53.7 mF/cm2. The electrocatalytic activity for hydrogen evolution reaction (HER) is strongly correlated with active edge sites and resulting efficient charge transport capability. Here, we presented a facile two-step method to synthesize 3D hierarchical NiS 2 /MoS 2 composite nanostructures on a carbon fiber paper (CFP) skeleton. The nanostructures distributed on CFP uniformly and composed of 2D nanosheets, which would provide plenty of active edge sites and increase the HER activity. Electrochemical measurement suggests that the prepared NiS 2 /MoS 2 exhibit great HER activity including a low overpotential of 102 mV, a small Tafel slope of 67 mV/dec, and a high double-layer capacity of 53.7 mF/cm2 in 1 M KOH aqueous solution. In addition, the HER activity is almost unchanged after galvanostatic technique with applied current densities of 10 mA/cm2 for 20 h. [ABSTRACT FROM AUTHOR]

Porous solid with multimodal pore size distribution provides plenty of advantages including large specific surface area and superior mass transportation to achieve high gas-sensing performances. In this study, α-Fe2O3nanoparticles with bimodal porous structures were prepared successfully through a nanocasting pathway, adopting the bicontinuous 3D cubic symmetry mesoporous silica KIT-6 as the hard template. Its structure and morphology were characterized by X-ray diffraction, nitrogen adsorption–desorption, transmission electron microscopy, and so on. Furthermore, the gas sensor fabricated from this material exhibited excellent gas-sensing performance to several volatile organic compounds (acetone, ethyl acetate, isopropyl alcohol, n-butanol, ethanol, and methanol), such as ultrahigh sensitivity, rapid response speed (less than 10 s) and recovery time, good reproducibility, as well as stability. These would be associated with the desirable pore structure of the material, facilitating the molecules diffusion toward the entire sensing surface, and providing more active sensing sites for analytical gas.

A series of ordered mesoporous chromium oxides (Cr2O3) were synthesized by first replicating bicontinuous cubic Ia3dmesoporous silica (KIT-6), then a controlled mesostructural transformation from Ia3dto I4132 symmetry during the replication from KIT-6 to Cr2O3was achieved by reducing the pore size and interconnectivities of KIT-6, accompanied with an increase in pore size from 3 to 12 nm and a decrease in framework thickness from 8.6 to 5 nm of the resultant Cr2O3replicas. The gas-sensing behavior of the Cr2O3replicas toward formaldehyde (HCHO) was systematically investigated. Ordered mesoporous Cr2O3with both large accessible pores (12 nm) and an ultrathin framework (5 nm) exhibits the best sensing performance, with a response (Rgas/Rair= 119) toward 9 ppm of HCHO 4.4 times higher than that (Rgas/Rair= 27) of its counterpart with small pores and a thick framework. Moreover, it possesses excellent selectivity for detecting HCHO over other interference gases such as CO, benzene, toluene, p-xylene, NH3, H2S, and moisture. The significantly enhanced sensing performance of ordered large-pore mesoporous Cr2O3with ultrathin framework suggests its great potential for the selective detection of HCHO.

There is an urgent demand for developing highly efficient bifunctional electrocatalysts with excellent stability toward the oxygen evolution and reduction reactions (OER and ORR, respectively) for rechargeable Zn–air batteries (ZABs). In this work, NiFe nanoparticles encapsulated within ultrahigh-oxygen-doped carbon quantum dots (C-NiFe) as bifunctional electrocatalysts are successfully obtained. The accumulation of carbon layers formed by carbon quantum dots results in abundant pore structures and a large specific surface area, which is favorable for improving catalytic active site exposure, ensuring high electronic conductivity and stability simultaneously. The synergistic effect of NiFe nanoparticles enriched the number of active centers and naturally increased the inherent electrocatalytic performance. Benefiting from the above optimization, C-NiFe shows excellent electrochemical activity for both OER and ORR processes (the OER overpotential is only 291 mV to achieve 10 mA cm–2). Furthermore, the C-FeNi catalyst as an air cathode displays an impressive peak power density of 110 mW cm–2, an open-circuit voltage of 1.47 V, and long-term durability over 58 h. The preparation of this bifunctional electrocatalyst provides a design idea for the construction of bimetallic NiFe composites for high-performance Zn–air batteries.

Mesoporous γ-Al2O3nanofiber was prepared viaa simple reverse precipitation route using Si-containing Al(OH)3and HNO3as raw materials. The resultant Si-containing mesoporous γ-Al2O3nanofiber exhibited high surface area of 320 m2/g, large pore volume of 1.17 cm3/g and large pore size of 10.5 nm. The introduction of Si element remarkably enhanced the thermal stability of mesoporous γ-Al2O3. The as-prepared nanofiber could maintain relative high surface area(110 m2/g) and pore volume(0.73 cm3/g) up to 1100 °C. The effects of various experimental conditions, such as pH value, reaction temperature and aging temperature on the structural properties of the mesoporous γ-Al2O3were also investigated.

Hydroxyapatite (HAP) microspheres composed of nanorods have successfully been prepared by a facile co‐precipitation method without any template. We propose the formation mechanism of the microspheres to be a four‐step process on the basis of the evolution of their morphology as a function of reaction time. We investigate the competitive sorption of the HAP microspheres for Pb2+, Cu2+, Cd2+, Zn2+, and Ni2+to show that HAP microspheres are a highly selective adsorbent for Pb2+in wastewater.

Abstract: Hierarchically ordered macro-mesoporous TiO2 films (Ti-Ma-Me) were fabricated on fluorine-doped tin oxide (FTO) substrates through the confinement self-assembly method. The prepared Ti-Ma-Me possesses periodically ordered structure and a large specific surface area, which was applied as an interfacial layer between the nanocrystalline TiO2 film (P25-TiO2) and FTO electrode in the dye-sensitized solar cell (DSSC). The introduction of a Ti-Ma-Me interfacial layer increased the shortcircuit current density (J sc) from 7.49 to 10.65 mA/cm2 and the open-circuit voltage (V oc) from 0.65 to 0.70 V as the result of its improved light harvesting efficiency by allowing for the high roughness factor and enhanced multiple internal reflection or scattering as well as reducing the back-transport reaction by blocking direct contact between the electrolyte and FTO electrode. Therefore, the photovoltaic conversion efficiency (η) was improved by 83% from 3.04% to 5.55%, as compared to a device using a bare P25 TiO2 photoanode.

A sphere of many coats: A facile sequential templating process for the general preparation of metal oxide hollow microspheres with multiple shells (red), such as α‐Fe2O3, Co3O4, NiO, CuO, ZnO, and ZnFe2O4, may open up new opportunities for preparing advanced materials based on complex hollow structures with multipurpose applications.

Schale auf Schale: Ein sequenzieller Templatprozess zur Herstellung von hohlen Metalloxid‐Mikrokügelchen mit mehreren Schalen (rot) aus α‐Fe2O3, Co3O4, NiO, CuO, ZnO und ZnFe2O4eröffnet einen neuen Weg zu fortgeschrittenen, kompliziert aufgebauten Materialien mit vielfältigen Anwendungsmöglichkeiten.

Hierarchically ordered macro−mesoporous titania films have been produced through a confinement self-assembly method within the regular voids of a colloidal crystal with three-dimensional periodicity. Furthermore, graphene as an excellent electron-accepting and electron-transporting material has been incorporated into the hierarchically ordered macro−mesoporous titania frameworks by in situreduction of graphene oxide added in the self-assembly system. Incorporation of interconnected macropores in mesoporous films improves the mass transport through the film, reduces the length of the mesopore channel, and increases the accessible surface area of the thin film, whereas the introduction of graphene effectively suppresses the charge recombination. Therefore, the significant enhancement of photocatalytic activity for degrading the methyl blue has been achieved. The apparent rate constants for macro−mesoporous titania films without and with graphene are up to 0.045 and 0.071 min−1, respectively, almost 11 and 17 times higher than that for pure mesoporous titania films (0.0041 min−1).

A general method has been developed for the synthesis of homogeneous hollow core−shell microspheres of spinel ferrites (MFe2O4, M = Zn, Co, Ni, Cd) by using carbonaceous saccharide microspheres as template. The products were characterized by X-ray powder diffraction, inductively coupled plasma-atomic emission spectroscopy, scanning electronic microscopy, transmission electron microscopy, and nitrogen sorption measurement. The effects of the concentration of metal salts have been studied using ZnFe2O4as an example. Increasing the concentration of metal salts could avoid the generation of impurity phase. The core size and shell thickness of hollow spheres obtained can be manipulated by changing the concentration of metal salts. Gas-sensor investigations revealed the ZnFe2O4hollow spheres used as gas-sensor materials possess high sensitivity and quick responses to organic gases such as ethanol.

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Solar steam generation has emerged as a promising technology for water purification. Carbon materials are the most widely investigated photothermal conversion materials, but it remains challenging to effectively improve the efficiency of carbon‐based photothermal films cost effectively. Herein, carbon nanotubes (CNTs)/polyvinyl alcohol (PVA) hybrid gels are designed by simply freezing/thawing the mixture of CNTs and the PVA polymers, in which the CNT light absorbers are well embedded in PVA molecular meshes. Combining the super‐hydrophilic feature and the capillary effect of the PVA porous networks, the hierarchical PVA gel enables efficient water transport from internal capillary channels to molecular meshes. Moreover, PVA molecule chains wrapped on the CNT light absorbers also function as energy‐absorbing media to reduce heat loss, achieving confinement of thermal energy to the water clusters. With this advanced solar steam generation system, the converted thermal energy can be utilized in situ to drive the vaporization of water around the CNTs. The CNTs/PVA hybrid gel shows a high energy efficiency of 90.5% and water evaporation rate of 2.06 kg m−2h−1under 1 sun illumination. In addition to taking advantage of the inherent bimodal porous structures, the fabricated evaporator can realize fast and long‐term stable solar steam generation. A polyvinyl alcohol (PVA)‐wrapped carbon nanotube hybrid gel with a high evaporation rate and energy efficiency is designed by means of a freezing/thawing process with crosslinkers. Due to the bimodal porous structure containing internal capillary channels and molecular meshes in the gel, it also achieves excellent salt‐resistant properties and long‐term stability.