Adsorption Reaction Research Articles

Copper Hexacyanoferrate Cathode as a Selective Adsorbent for Ammonium Ions in Sodium-Rich Solutions

Abstract Ammonium ion remediation has led to innovative methods, such as Faradaic redox reaction using Prussian blue. Our approach uses an adsorption reaction that is controlled by electric current instead of potential. By sweeping the potential through current control, selective adsorption of NH4+ was achieved in solutions with high concentrations of Na+ (ca. 1:50). The use of thick electrodes enabled ammonium levels to be reduced to environmentally acceptable levels in three steps, even from highly concentrated solutions of NH4+ (200 mmol/L).

Enhancing catalytic oxidation of benzene with Cu-Doped MnO2: Insights into structural defects and electronic modifications

The present research focuses on the role of copper (Cu) doping in enhancing the catalytic efficacy of manganese dioxide (α-MnO2) for benzene oxidation, a representative volatile organic compound (VOC). Despite the abundance and low cost of MnO2, its pristine form requires improvement for industrial VOC oxidation processes. Utilizing a range of characterization methods, the study reveals that Cu doping generates oxygen vacancies and increases the Mn3+ content within the catalyst structure, which are crucial for enhancing the adsorption and activation of reactants. The findings indicate that Cu-doped α-MnO2 exhibits superior catalytic activity and lower activation energy for benzene oxidation compared to the undoped counterpart. The electronic interactions induced by the doping of Cu and the effect on the catalytic process are demonstrated and discussed in depth. This work emphasizes the strategic importance of dopant optimization and contributes to the advancement of MnO2-based catalysts for environmental remediation, aligning with goals of environmental protection and human health safety.

Rational Design of Diatomic Active Sites for Elucidating Oxygen Evolution Reaction Performance Trends.

Diatomic catalysts, especially those with heteronuclear active sites, have recently attracted significant attention for their advantages over single-atom catalysts in reactions with relatively high energy barrier, e.g. oxygen evolution reaction. Rational design and synthesis of heteronuclear diatomic catalysts are of immense significance but have so far been plagued by the lack of a definitive correlation between structure and catalytic properties. Here, we report macrocyclic precursor constrained strategy to fabricate series of transition metal (MT, Ni, Co, Fe, Mn, or Cu)-noble (MN, Ir or Ru) centers in carbon material. One notableperformance trend is observed in the order of Cu-MN < Mn-MN < Fe-MN < MN < Co-MN < Ni-MN. However, thepathway has been not altered, still following the traditional adsorption reaction mechanism. The effect of the MT atoms on theperformances could possibly originate from the distinct adsorption/desorption behaviors of key intermediates (i.e. *OH, *O and/or *OOH), strongly implying that ΔG*OOH-ΔG*OH could be used as the performance descriptor. We believe that our work provides useful strategy for synthesis of diatomic active sites with sole coordination configuration and varied composition, and in-depth insight to their catalytic mechanism, which could be used for further optimization of diatomic catalysts towards oxygen electrocatalysis.

Exploring performance and mechanism of modified metal-organic frameworks in calcium alginate/polyvinyl alcohol double-network hydrogels for effective dye wastewater treatment

To address the growing problem of dye wastewater pollution, a novel MOFs adsorbent calcium alginate/polyvinyl alcohol@UiO-66 was developed using environmentally friendly polymers, sodium alginate and polyvinyl alcohol creating gel spheres with a double-network structure through cross-linking. UiO-66 metal-organic frameworks are then grown onto the gel spheres, resulting in the final CA/PVA@UiO-66 adsorbent. This adsorbent boasts a high surface area (17.4 m2/g) and a mesoporous-nested microporous structure. It effectively removes MB from water, the actual maximum adsorption capacity was measured at 275.8 mg/g, which surpasses most existing adsorbents. Remarkably, the adsorbent retains 93.9 % of its initial capacity even after 10 reuse cycles. The adsorption process adhered to the Redlich-Peterson model and the PFO model. The N2-Sorption isotherm, actual Methylene blue (MB) adsorption experiments, and model analysis further suggest that the adsorption process is a complex heterogeneous diffusion process involving simultaneous chemical and physical adsorption. Additionally, the adsorption process is endothermic, indicating that it can occur spontaneously at 298 K. Increasing the temperature promotes the forward progress of the adsorption reaction, thereby enhancing the adsorption capacity. The gel adsorbent exhibited excellent dye wastewater purification capabilities, coupled with commendable reusability.

Mechanism of CeO2 modified CO2 adsorbent with SO2 resistance: Experimental and DFT study

The flue gas emitted from coal-fired boilers contains a trace amount of SO2 after desulfurization, resulting in poor performance of CO2 adsorbent. In this paper, CO2 adsorption performance of potassium adsorbent modified by CeO2 doping and the effect of SO2 on CO2 adsorption were investigated by simulated flue gas. Theoretical research on the reaction between SO2 and CO2 with dopant was conducted by Density Functional Theory (DFT) method. The results showed that the cumulative CO2 adsorption capacity of the 4% Ce doped adsorbent without SO2 and with SO2 were 10.2% and 53.6% higher than that of the undoped adsorbent. The oxygen vacancy could cause the f orbital of Ce to exert greater influence, making the surface properties more unstable. The activation energy of the adsorption reaction between SO2 and H2O on Ce doped adsorbent was 266.5 kJ/mol, and there were three transition states in this reaction, with O vacancy formation as the rate-controlling step.

Insights into the mechanism of enhancing resistance of MnAlOx-Str NH3-SCR catalyst derived from streptomycin waste residue and LDHs

Streptomycin waste residue composited with Layered double hydroxides (LDHs) derived Mn1Al1Ox-Str-2 catalyst was proposed for NH3 selective catalytic reduction (NH3-SCR) denitration technology, which improved the overall catalytic performance. In the wide temperature range of 150-300℃, the preferred Mn1Al1Ox-Str-2 catalyst had Nitrogen oxides (NOx) conversion of exceeded 96%, which was higher than that of the control Mn1Al1Ox and Mn/Al2O3 catalysts. In addition, Mn1Al1Ox-Str-2 catalyst had better resistance to SO2 and/or H2O, as well as good regeneration ability. Various analytical techniques had confirmed that the Mn1Al1Ox-Str-2 catalyst derived from streptomycin residue composite LDHs precursor had better surface properties with more active species, abundant surface oxygen, higher reduction capacity and better adsorption of NOx and NH3. Analytical techniques revealed that the Lewis acid site on the surface of Mn1Al1Ox-Str-2 catalyst was involved in SCR reaction and both the Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism existed simultaneously in the NH3-SCR reaction, and SO2 had a weak effect on the adsorption of reactants with fewer sulfate species formation. This work provided feasible strategies for efficient and stable SCR technology and efficient utilization of streptomycin residue waste resources, which was significant for the design and application of SCR technology in the future.

Insights into the Effect of Crystal Facets and Sulfur Defects on the Product Selectivity of Various CdS Configurations for CO2 Photoreduction: A DFT Study

CO2 photoreduction into valuable hydrocarbons, such as CO, CH4, and C2H4, delivers a promising approach to address both environmental and energy challenges. Transition metal chalcogenides, particularly cadmium sulfide (CdS), have emerged as prominent candidates due to their tunable electronic properties and availability. This study delves into a comprehensive investigation of how CdS crystalline facets and sulfur-deficient surfaces modulate the product selectivity. Through employing density functional theory (DFT), we unravel the catalytic performance of various CdS crystal orientations and sulfur vacancy configurations. The results have shown that different CdS facets exhibit unique electronic characteristics and surface energetics, which influence the adsorption dynamics and reaction pathways. The introduction of sulfur vacancies further modulates the nature of active sites, leading to substantial shifts in product selectivity. A detailed investigation on the reaction mechanisms unveils that specific facets preferentially facilitate the formation of CO, while others are more conducive to the generation of hydrocarbons such as CH4 and C2H4, due to the variations in activation barriers and intermediate stabilities. These findings underscore the importance of crystal facet engineering and defect manipulation in tailoring catalyst performance thus providing valuable insights for the rational design of efficient and selective CO2 reduction metal catalysts.

Heterogeneous precipitation behavior and mechanism during the adsorption of cationic heavy metals by biochar: Roles of inorganic components

Heavy metals are commonly adsorbed by biochar in contaminated water and soil. However, the behaviour and underlying mechanisms of heterogeneous precipitation between the inorganic components of biochar and cationic heavy metals remain poorly understood. In this study, we comprehensively investigated the nucleation, growth, and aggregation of precipitates, ion exchange-coupled precipitation behaviour, adsorption-precipitation correlation, and the influence of environmental factors (e.g., anion content, pH, initial concentration, type of heavy metals, and biochar size). The kinetic results indicated that the generation of precipitates was accompanied by an adsorption reaction with a gradual increase in crystal size and aggregation behaviour. Moreover, precipitation includes both surface and solution precipitation. The increasing local concentration of Pb(II) around the biochar at high initial concentrations increased the supersaturation of the nucleating substance, which decreased the potential for heterogeneous nucleation and facilitated heterogeneous precipitation. Correlation analysis revealed the presence of a coupling mechanism between precipitation and cation exchange. The enhanced electrostatic attraction at high pH could lower the heterogeneous nucleation potential barrier, thus promoting heterogeneous precipitation. The small biochar size extended the induction time, which was unfavourable for heterogeneous nucleation. This study provides a deeper understanding of the heterogeneous precipitation behaviour of the inorganic components of biochar and cationic heavy metals.

Construction of 0-dimensional silver quantum dot/MoSe2@MXene/3-dimensional porous copper foam composite electrodes with heterogeneous interfaces for synergistic electrocatalytic degradation of antibiotics

This study proposes a novel and efficient Ag quantum dots (QDs)/MoSe2@two-dimensional transition metal carbide/nitride (MXene)/copper foam (CF) composite electrode to address the challenge of electrocatalytic degradation of antibiotics in water. The electrode formed a unique electron donor–acceptor system by loading Ag QDs and heterostructured nanosheets on CF, significantly facilitating charge transfer and segregation at the interface. The catalytically active sites at the edges and defective locations of MoSe2 in conjunction with the two-dimensional MXene structure, which formed an efficient electron transfer channel, promoted the electron transfer from the interior to the surface and accelerated the hydrogen adsorption and reduction reactions. Moreover, the charge redistribution at the interface of Ag QDs and MoSe2@MXene formed interfacial dipoles, increasing the active sites on the catalyst surface and promoting the generation of cathodic atomic hydrogen (H*). Under optimal conditions, the degradation rate of tigecycline (TGC) reached as high as 90.1 % ± 2.4 % within 60 min. The anode-generated OH and HClO, along with the cathode-generated H, further promoted the degradation of TGC through co-catalysis. The degradation pathways were analyzed using density-functional theory (DFT) calculations and liquid chromatography-mass spectrometry (LC-MS) techniques. Moreover, toxicity analysis of the degradation products was carried out to ensure the safety of the treated wastewater discharge. A reflux continuous effluent reactor was also designed to achieve high degradation efficiency and low energy consumption after stable operation, laying the foundation for industrial applications. This technology provides new ideas for the design of green, efficient, stable, and low-consumption electrocatalytic reactors and contributes to a sustainable future environment.

Heterogeneous Fenton system driven by magnetic graphene-like biochar for degrading tetracycline

In this study, a novel catalyst with high efficiency and low cost was synthesized from farmland waste peanut shells by one-step pyrolysis modification method via K2FeO4, and employed for the catalytic degradation of tetracycline (TC). The magnetic potassium ferrate modified graphene-like biochar catalyst (PFGB) exhibited a high porosity, a highly graphitized structure, and a large specific surface area (857.09 m2·g-1) which was almost 30 times higher compared with peanut shell biochar, and were found to contain more functional groups. The formation and distribution of Fe3O4 and Fe0 nanoparticles on the surface/pores of PFGB provided more active sites for promoting adsorption and catalytic degradation reactions, and accelerated Fe(II)/Fe(III) recycle. Under the optimal conditions (pH=3.5, catalyst dosage = 0.5g·L-1, H2O2 concentration = 10mmol·L-1), about 98% of TC were degraded within 90min when the initial concentration of TC was 150mg·L-1, and PFGB could perform effectively over a wide pH range of 3-6. Furthermore, PFGB exhibited the advantages of convenient magnetic separation and strong reusability, maintaining a TC removal rate of ~90% after five cycles of experiments. The results of free radical quenching experiment and electron spin resonance analysis revealed that •OH and 1O2 were the main active species in the radical and non-radical pathways, respectively. This study indicated that PFGB, a catalyst developed for heterogeneous Fenton-like systems, possessed high efficiency, stability and reusability, and could be promising for the removal of TC in wastewater and other polluted waters.

Remediation of heavy metal contaminated soil in mining areas with vaterite-type biological calcium carbonate

In recent years, research on the remediation of heavy metal contaminated soil by microbially induced carbonate precipitation (MICP) technology has yielded significant findings. However, when utilizing MICP for remediation in situ, urea and calcium chloride may produce high concentrations of NH4+ and Cl-, which subsequently cause secondary pollution. If the biological calcium carbonate (Bio-CaCO3) produced by MICP is employed as a highly efficacious adsorbent, secondary pollution can be avoided while remediating heavy metal pollution. In this study, vaterite-type Bio-CaCO3 was prepared under the regulation of sophorolipids, and the remediation effect and mechanisms for heavy metal contaminated soil were investigated. The results demonstrated that sophorolipids facilitate the formation and stabilization of vaterite-type Bio-CaCO3. The addition of vaterite-type Bio-CaCO3 could notably increase the content of soil organic matter, enhance soil urease activity, and reduce soil catalase activity. On the 30th day of remediation with vaterite-type Bio-CaCO3, the active state content of Pb and Cd in the soil exhibited a decrease of 41.23% and 35.00%, respectively. Additionally, the exchangeable state content demonstrated a reduction of 6.61% and 8.48%, while the carbonate-bound state exhibited an increase of 12.05% and 13.89%, respectively. The principal mechanisms for the remediation of heavy metal contaminated soil by vaterite-type Bio-CaCO3 may be attributed to ion exchange, chemical precipitation, physical adsorption, and complexation reactions. The analysis of the microbial community structure demonstrated that vaterite-type Bio-CaCO3 could enhance the abundance of multiple genera with urease-producing genes, including Pseudomonas, Staphylococcus, and Bacillus while maintaining the soil biodiversity. This study provides a new idea for the remediation of heavy metal contaminated soil around the mining area and offers technical support for the construction of green mines.

Highly efficient selective hydrogenation of furfural to tetrahydrofurfuryl alcohol over MOF-derived Co-Ni bimetallic catalysts: The effects of Co-Ni alloy and adsorption configuration

The targeted conversion of furfural (FA) over inexpensive catalyst is a critical and challenging project. Herein, CoNi alloy catalysts (xCoyNi/C) were prepared through one-step pyrolysis of metal–organic frameworks and used in furfural (FA) hydrogenation to tetrahydrofurfuryl alcohol (TFOL). The formation of CoNi alloy leads to a reconfiguration of the electronic structure on the metal surface, which affects the adsorption of functional groups on FA and furfuryl alcohol (FOL). In situ FT-IR analysis and DFT calculations verify that bimetallic CoNi alloy catalyst exhibits more suitable reactants adsorption and hydrogenation rate in comparison with the monometallic Co and monometallic Ni catalysts. Meanwhile, CoNi alloy significantly reduces the activation barrier from FOL to TFOL. Hence, the 1Co1Ni/C catalyst gives the highest TFOL yield of > 99 %. This study provides a simple strategy for the preparation of alloy catalysts for tuning product selectivity and presents practical potential for upgrading biomass-derived platform molecules.

Experimental and modeling studies on char combustion under pressurized O2/H2O conditions

The desorption kinetic parameters for pressurized combustion and gasification reactions were determined based on a C++ program coupled with the Langmuir-Hinshelwood (L-H) kinetic model developed and experimental data from pressurized char combustion, and the established L-H kinetic model for pressurized char-O2/H2O combustion was refined in the current paper. The activation energy for desorption in reactions involving pressurized char-O2 and char-H2O was determined to be 250.8 kJ/mol, accompanied by a pre-exponential factor of 5.42×1010 g/(m2 s). Using this foundation, the current research conducted simulations to investigate the impacts of temperature, pressure, and H2O concentration on the oxidation adsorption rate (Rads,oxi), desorption rate (Rdes), gasification adsorption rate (Rads,gas), and the competitive influences of kinetics and diffusion processes within the pressurized char-O2/H2O combustion. The simulation results indicate a gradual increase in Rdes and Rads,gas with char conversion to reach a peak, followed by a gradual decline. Conversely, the Rads,oxi varies smoothly throughout the char conversion process. At 1673 K/1.0 MPa, the char-O2/H2O reaction rate is primarily constrained by Rads,oxi and Rads,gas, with the adsorption reaction serving as the rate-controlling step. Moreover, it was noted that a rise in pressure resulted in a linear increase in Rads,oxi, Rdes, and Rads,gas. At elevated temperatures, the impact of pressure on them becomes more noticeable. However, the introduction of H2O mitigates this effect. Elevated temperature and pressure facilitate the competition on the kinetics of char-O2 combustion for O2 diffusion, resulting in the conversion of char being more susceptible to O2 diffusion rate limitation. With the addition of 20% H2O, the competition effect was weakened. In the case of pressurized combustion involving char and O2/H2O, the char conversion is primarily constrained by the O2 diffusion rate and is scarcely influenced by the H2O diffusion rate.

Evaluation, optimization study, and life cycle assessment of novel eco-friendly PVA-based nanocomposite hydrogel adsorbents for methylene blue and paracetamol removal

In this study, an eco-friendly and novel hydrogel based on a crosslinked polyvinyl alcohol (PVA), iota carrageenan (IC) and polyvinylpyrrolidone (PVP) scaffold, containing a large amount (10–50 wt%) of nanoscale palm fronds (NPF) as additives, for water purification was demonstrated. A life cycle assessment (LCA) findings on NPF as biomass waste incorporated into PVA_PVP_IC polymer matrix was presented, and the results highlight the necessity of focused actions to reduce environmental impact and support the palm waste utilization in a sustainable manner. The multicomponent nanocomposite hydrogels were examined as adsorbents in a system work in batches for methylene blue (MB) and paracetamol (PCT) removal. The results show that, the presence of NPF, which dispersed in the hydrogel PVA_PVP_IC scaffolds containing both covalent and non-covalent cross-linking bonds, greatly enhanced the MB and PCT adsorption efficiency. A response surface methodology (RSM) model was used to find the best operating parameters of contaminant adsorption, including time, adsorbent dose, and starting concentration of pollutants. By using this statistical model, it was found that the optimal conditions for the adsorption reaction to achieve the complete removal of MB are 66.7 h adsorption time duration, 98.5 mg L−1 starting concentration, and an adsorbent dose of 5.9 mg, while for the complete removal of PCT, it is 57.6 h adsorption time duration, 80 mg L−1 starting concentration, and an adsorbent dose of 6 mg. The reusability of the nanocomposite hydrogels were tested for 5 cycles, all showed high adsorption capacity, indicating the potential for practical application of this nanocomposite hydrogel system. This study indicates that the prepared nanocomposite hydrogel raises the standard used for treatment of wastewater and also gives a solution to protect the environment and mitigate global warming.

The role of carbon textile surface functionalities in reactive adsorption of vapor and liquid 2-chloroethyl ethyl sulfide: Evaluating interactions at the interface

A carbon textile (CT) was chemically modified to increase its surface activity and promote the adsorption and degradation of 2-chloroethyl ethyl sulfide (CEES) - a surrogate for mustard gas. CT was initially subjected to oxidation (CTO), and then heated under ammonia (CTON) or hydrogen sulfide (CTOS) atmosphere to incorporate nitrogen or sulfur functionalities, respectively. Detoxification experiments were performed in closed vials using either vapor or liquid forms of CEES. The maximum vapor weight uptakes on CT, CTO, CTOS, and CTON were 399, 372, 434, and 489 mg/g, respectively. All textiles were able to prevent the vaporization of CEES liquid droplets. Although similar reaction products were detected in both vapor and liquid systems, the marked differences in the extent of CEES chemical transformation on the surfaces of the textiles indicate distinct detoxification pathways influenced by surface chemistry. Even though the heterogeneous surface of CTO, enriched with oxygen surface groups, facilitated various reactions, hydrolysis was the predominant pathway. The thermal treatment, regardless of the atmosphere, reduced the oxygen content, decreasing the extent of hydrolysis. However, incorporating basic surface groups such as pyridines, amines, or weak acids such as thiols promoted dehydrohalogenation as the main detoxification pathway on these samples.

Enhancing Europium Adsorption Effect of Fe on Several Geological Materials by Applying XANES, EXAFS, and Wavelet Transform Techniques.

This study conducted adsorption experiments using Europium (Eu(III)) on geological materials collected from Taiwan. Batch tests on argillite, basalt, granite, and biotite showed that argillite and basalt exhibited strong adsorption reactions with Eu. X-ray diffraction (XRD) analysis also clearly indicated differences before and after adsorption. By combining X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and wavelet transform (WT) analyses, we observed that the Fe2O3 content significantly affects the Eu-Fe distance in the inner-sphere layer during the Eu adsorption process. The wavelet transform analysis for two-dimensional information helps differentiate two distances of Eu-O, which are difficult to analyze, with hydrated outer-sphere Eu-O distances ranging from 2.42 to 2.52 Å and inner-sphere Eu-O distances from 2.27 to 2.32 Å. The EXAFS results for Fe2O3 and SiO2 in argillite and basalt reveal different adsorption mechanisms. Fe2O3 exhibits inner-sphere surface complexation in the order of basalt, argillite, and granite, while SiO2 forms outer-sphere ion exchange with basalt and argillite. Wavelet transform analysis also highlights the differences among these materials.

Thermal index parameter investigation of coal–oxygen adsorption during low-temperature oxidation of coal

Oxidative spontaneous combustion is an inherent property of coal. In which, coal oxygen adsorption heat is the decisive speed step of coal spontaneous combustion self-acceleration process, and coal oxygen adsorption heat is closely related to coal pore structure. By utilising an automatic physicochemical adsorption instrument, it was found that the form of pore existence in coal was dominated by mesopores, that the pore structure, oxygen uptake capacity and temperature varied non-linearly, and that pore size was positively correlated with pore volume; Using a self–built air adsorption calorimetric experimental system, it was found that when oxygen was involved in the adsorption reaction, the presence of oxygen would lead to a significant time lag in the adsorption equilibrium. Additionally, the transition temperature of coal adsorption mode has been determined to be 40 °C, shedding light on the mechanism behind the thermal self-accelerating reaction of coal oxygen adsorption; Using the correlation method, it was obtained that the index affecting the physical adsorption heat release is the percentage of mesopore volume in the coal, while the index affecting the chemical adsorption heat release is the pore size. The research findings are anticipated to offer theoretical backing for advancing flame-resistant materials.

Improving photoelectrochemical performance of transferred TiO2 nanotubes onto FTO substrate with Mo2C and NiS as Co-catalyst

The photoelectrochemical (PEC) performance of titanium dioxide nanotube (TiO2 NT) photoelectrodes for sustainable hydrogen production has garnered significant research interest. Despite the advantages of TiO2 NT fabricated via anodization of titanium metal, such as their well-ordered vertical structure, challenges persist including the thick oxide barrier layer, limited optical transparancy, and the wide energy band gap (∼3.0 eV), which constrain their practical efficiency in PEC applications. This study addresses these limitations by introducing a novel approch to transfer TiO2 NT onto a fluorine-doped tin oxide (FTO) substrate. TiO2 NTs were synthesized with varying anodization times and steps to achieve optimal free-standing structures. To further enhance PEC performance, co-catalyst including molybdenum carbide (Mo2C) and nickel sulfide (NiS) were incorporated using immersion and successive ionic layer adsorption reaction (SILAR) methods, respectively. Comprehensive characterization using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) provided insights into the crystal phase, morphological structure, band gap, and elemental composition of the photoelectrodes. Photoelectrochemical and photostability evaluations were conducted through linear scan voltammetry (LSV) and chronoamperometry under dark and light conditions. Results indicate that transferring TiO2 NTs onto FTO significantly enhanced photocurrent density, achieving a 2.5-fold increase at 0.7 V versus a TiO2 NT/Ti substrate. The incorporating of co-catalysts Mo2C, NiS and the combined NiS/Mo2C further enhanced the photocurrent density to 2.20, 3.00 and 8.00 mA cm−2 respectively, with a remarkable 31-fold enhancement compared to the TiO2 NT/Ti substrate. This findings underscore the potential of the TiO₂ NT/FTO photoelectrode with optimized co-catalyst integration for advanced photoelectrochemical applications.

Effects of oxygen consumption characteristics of goaf on the low oxygen formation mechanism in the working face

Low oxygen at a coal mine's working face has a detrimental impact on working conditions and productivity. This study conducted an experiment on oxygen consumption at low temperatures, quantified the rate of air infiltration, and scrutinised and examined the zoning division of coal seam gas occurrences. The gas change rules in the return air corner and the goaf and the gas outflow rules in the goaf to the working face are analysed. Experiment results reveal that residual coal predominantly consumes oxygen through a combination of physical adsorption and chemical reaction, which is the key factor in the decrease in oxygen concentration. The examination showed, that the gas emission rate of air from the surface cracks to the working face is 0.09–0.13 m·s−1. Air leakage in the goaf results in the oxidation of residual coal and consequently leads to significant oxygen consumption. The release of low-oxygen gases from the oxidation of residual coal in the goaf to the working face is facilitated by atmospheric pressure and negative pressure ventilation methods, which act as sources of power. The research findings offer direction for examining and managing the problem of low oxygen in coal mine working faces.

Interfacial Electronic Interactions Promoted Activation for Nitrate Electroreduction to Ammonia over Ag‐Modified Co3O4

AbstractElectrocatalytic nitrate (NO3−) reduction to ammonia (NRA) offers a promising pathway for ammonia synthesis. The interfacial electronic interactions (IEIs) can regulate the physicochemical capabilities of catalysts in electrochemical applications, while the impact of IEIs on electrocatalytic NRA remains largely unexplored in current literature. In this study, the high‐efficiency electrode Ag‐modified Co3O4 (Ag1.5Co/CC) is prepared for NRA in neutral media, exhibiting an impressive nitrate conversion rate of 96.86 %, ammonia Faradaic efficiency of 96.11 %, and ammonia selectivity of ~100 %. Notably, the intrinsic activity of Ag1.5Co/CC is ~81 times that of Ag nanoparticles (Ag/CC). Multiple characterizations and theoretical computations confirm the presence of IEIs between Ag and Co3O4, which stabilize the CoO6 octahedrons within Co3O4 and significantly promote the adsorption of reactants (NO3−) as well as intermediates (NO2− and NO), while suppressing the Heyrovsky step, thereby improving nitrate electroreduction efficiency. Furthermore, our findings reveal a synergistic effect between different active sites that enables tandem catalysis for NRA: NO3− reduction to NO2− predominantly occurs at Ag sites while NO2− tends to hydrogenate to ammonia at Co sites. This study offers valuable insights for the development of high‐performance NRA electrocatalysts.