A simple and efficient strategy to suppress soot from acetylene diffusion flames by inserting metal cage into the flame is reported in this work. The influence of various factors on the soot suppression efficiency of acetylene diffusion flame are investigated, including metal cage height above burner (CHAB), mesh number, material of the metal cage, diameter of the metal cage, acetylene flow rate, burner nozzle inner diameter and metal cage structures. It is found from experimental work and temperature simulation results that inserting the metal cage into the flame splits it into two parts. The temperature in the lower region of the metal cage drops significantly, reducing soot formation. Conversely, the temperature in the upper region rises, promoting soot oxidation. Schlieren imaging and flow field simulation reveals that air enters the flame through the pores of the metal cage, enhancing fuel-air mixing and further suppressing soot formation. It is also found that soot suppression efficiency is closely related to the contact area between the flame surface and the metal cage. When the metal cage extends into the flame, soot accumulates on it, and while soot suppression is possible, it takes time. If the contact area is too small, soot suppression is incomplete. However, increasing the contact area improves efficiency. The geometry of the metal cage has a significant impact on soot suppression. Notably, a cylindrical metal cage (7 mm diameter, 14-mesh) in contact with the flame surface achieve efficient heat transfer and rapidly suppresses soot when the normalized CHAB (CHAB divided by flame length without the metal cage) reaches 0.3.

In this work, by employing NH4F as a structure-directing agent (SDA) and VO(acac)2, we have manipulated the morphology of Co3O4, leading to the creation of a novel hexagram-like structure with exceptional evenness in distribution. To comprehend the growth mechanism and elucidate the functions of various agents involved, experiments were conducted under diverse conditions with varying reagent ratios. The results indicate that, under the influence of NH4F as the structure-directing agent (SDA), the hexagram-shaped Co3O4 structure exhibits sensitivity to both reaction time and temperature, implying that its growth mechanism is regulated by the Kirkendall effect and involves partial cation exchange. Additionally, with alteration of reagent ratios, Co3O4 with ball-flower morphology was synthesized successfully. Through cross-section SEM examination, the observed growth mechanisms for both the hexagram and ball-flower structures were substantiated. Lastly, electrochemical performance tests of the hexagram and ball-flower structures on SC electrode were carried out, and specific capacitances were 452 C/g (1062 F/g) and 696 C/g (1339 F/g), respectively. The hexagram-shaped Co3O4 structure displays exceptional SC electrode material characteristics, retaining an outstanding capacitance of 93.1% even after 10,000 cycles, highlighting its superior cycle performance. This paper hopes to inspire further SC electrode materials studies based on its novel morphology modulation strategy.

In this work, highly microporous nitrogen-enriched carbon materials were prepared from ZIF-11 through alkali-assisted carbonization using either KOH or NaOH. By adjusting the alkali species, the additive-to-precursor mass ratio, and the pyrolysis temperature, the pore architecture and surface chemical characteristics of the resulting carbons were deliberately regulated in a systematic manner. Thermogravimetry-infrared (TG-IR), pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), and kinetic evaluations collectively demonstrate that KOH substantially redirects the thermal decomposition route: it induces earlier CO2 evolution, inhibits the generation of hydrocarbon products, and thereby promotes the formation of ultramicropores with apertures of approximately 5–7 Å, while concurrently improving surface chemical features. Multiple linear regression together with correlation analyses further indicate that pore volume within the 5–7 Å interval is the primary structural descriptor controlling CO2 adsorption at 25 °C and 1 bar, whereas pyrrolic nitrogen emerges as the most important functional-group contributor. Under optimized conditions, the sample denoted 2ZIF-11-KOH-700 delivers CO2 uptake values of 4.72 mmol/g at 25 °C and 1 bar, and 7.49 mmol/g at 0 °C and 1 bar, along with a high CO2/N2 selectivity of 39.92 and robust performance over repeated cycles. Overall, these results offer an implementable synthetic route and mechanistic insights that support the rational design of high-efficiency carbon-based adsorbents for CO2 capture.

Accurate prediction of fly ash unburned carbon content remains a major technical bottleneck for combustion optimization in smart power plants, especially for W-flame boilers firing low-reactivity anthracite. This study establishes a high-fidelity CFD-DPM framework for a 622 MW subcritical W-flame boiler in ANSYS Fluent by coupling Eulerian gas-phase simulation with Lagrangian stochastic particle trajectory tracking via the Discrete Phase Model. The standard k-epsilon turbulence model, non-premixed combustion with PDF transport, and P1 radiation model are employed, while fly ash unburned carbon content is quantitatively derived from DPM mass-weighted burnout efficiency. Validated against operational boiler data with relative error below 6%, the model reveals pronounced nonlinear correlations: primary air velocity follows a J-shaped curve with minimum unburned carbon content of 3.45% at 14.9 m per second, secondary air exhibits a U-shaped profile with minimum of 3.17% at 26.9 m per second, and overfire air exerts only marginal effects around 3.1%. Field implementation of the optimized parameters reduced measured unburned carbon content from 4.22% to 3.29%, corresponding to a 22% improvement in burnout efficiency. Complementary SEM-EDS analysis elucidates spatial slagging heterogeneity driven by furnace temperature gradients and coal ash mineralogy. This innovative DPMbased predictive framework, rigorously validated through both numerical and field experiments, provides a robust tool for real-time unburned carbon content control and intelligent combustion management in coal-fired power plants.

Putty powder-based hydroxyapatite (P-HAP) was synthesized hydrothermally from high-calcium waste putty powder as the calcium source and characterized by XRD, FTIR, SEM, EDS, BET, and zeta potential analyses. The effects of P-HAP dosage and pH on the adsorption of Mn2+, Fe2+, COD, and NH3-N from black and odorous wastewater were investigated. At a dosage of 1.6 g/L and pH = 10 (CFe2+ = 10 mg/L, CMn2+ = 100 mg/L, CCOD = 50 mg/L, CNH3-N = 50 mg/L, 25 °C), the maximum adsorption capacities were 61.24, 6.25, 21.00, and 21.86 mg/g for Mn2+, Fe2+, COD, and NH3-N, respectively; the adsorption efficiencies of Fe2+ and COD reached 100% and 67.18%. At a dosage of 4 g/L and pH = 7, under the same conditions, the adsorption efficiencies for Mn2+ and NH3-N reached 100% and 73.92%, respectively. The adsorption conformed to the pseudo-second-order kinetics and the Freundlich isotherm models, indicating multilayer heterogeneous surface chemical adsorption. The adsorption mechanisms primarily involve complexation reactions and ion exchange. A quantitative model for predicting dosage was also established. This provides a new approach for the resource utilization of waste putty powder, also for the efficient, low-cost, and environmentally friendly treatment of black and odorous water bodies.

Waste putty powder-derived hydroxyapatite (P-HAP) was synthesized via a chemical precipitation method using waste putty powder as the calcium source. The adsorption performance and mechanisms of P-HAP for the removal of potentially toxic elements, including Cd(ii), Pb(ii), and Cr(vi), from aqueous solutions were investigated. The underlying adsorption mechanisms were elucidated using XRD, SEM, EDS, and FT-IR analyses. The results showed that: ① under a P-HAP dosage of 1.6 g L-1 and a temperature of 25 °C, the adsorption capacity of P-HAP for Pb(ii) reached 62.50 mg g-1, with a removal efficiency of 100%, at an initial Pb(ii) concentration of 100 mg L-1 and pH 4. Under an initial Cd(ii) concentration of 100 mg L-1 and pH 10, the adsorption capacity for Cd(ii) was 40.63 mg g-1, with a removal efficiency of 65.00%. For Cr(vi), at an initial concentration of 10 mg L-1 and pH 4, the adsorption capacity was 1.43 mg g-1, corresponding to a removal efficiency of 22.94%. ② The adsorption behavior of the three potentially toxic elements (PTEs) was better described by the Langmuir isotherm and pseudo-second-order kinetic models. The adsorption of Pb(ii) and Cd(ii) onto P-HAP primarily occurred through dissolution-precipitation, surface complexation, and ion exchange, whereas the adsorption of Cr(vi) was dominated by surface complexation. In addition, electrostatic attraction has a synergistic effect on the adsorption process.

This study presents a comprehensive investigation into the pyrolysis mechanism of ZIF-8 and elucidates the regulatory role of KHCO3 during its pyrolysis. Using TG-IR, Py-GC/MS, and Coats-Redfern kinetic analysis, the pyrolysis of ZIF-8 proceeds in three distinct stages: desorption of residual species (<213.9 degrees C), framework collapse with Zn2+ to ZnO conversion (213.9-716.5 degrees C), and continuous carbonization (>716.5 degrees C). During the main stage, the apparent activation energy sharply increases from 45.94 kJ/mol to 294.45 kJ/mol and further to 630.68 kJ/mol, which reflects the sequential cleavage of coordination bonds, imidazole rings, and Zn-O lattices. Py-GC/MS analysis shows the volatile products from ZIF-8 pyrolysis primarily consist of HCs, NCs, and OCs. These substances originate mainly from the pyrolysis and rearrangement reactions between the 2-MIM ligand and residual TEA. KHCO3 introduction lowers the initial decomposition temperature from 213.9 to 136.7 degrees C. Its decomposition products (e.g., K2CO3, CO2) regulate pyrolysis kinetics, reducing the apparent activation energy in the mid-to-high temperature stage from 294.45 kJ/mol to 97.39 kJ/mol. Furthermore, KHCO3 inhibits ZnO formation and optimizes nitrogen-containing gas evolution by promoting NH3 release while suppressing HCN and HNCO at high temperatures. It also simplifies product composition, reducing N-heterocyclics and amines while catalyzing organic conversion to CO2 or graphitic carbon. This study explains the complex pyrolysis chemistry of ZIF-8 at the molecular level. The KHCO3-assisted regulation strategy provides a sustainable method for customizing nitrogen-doped carbon, reducing the impact on the environment and enhancing the functionality of energy and environmental applications.

In this study, the pyrolysis mechanism and kinetics of lychee seeds (LS) and the profound regulatory role of KOH are systematically investigated. Integrated analytical techniques, including thermogravimetric (TG), CoatsRedfern (CR) kinetic modeling, thermogravimetric-infrared spectrometer (TG-FTIR), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) were employed to elucidate the profound impact of KOH on the pyrolysis pathways and product distribution. The addition of KOH profoundly influences pyrolysis behavior. It not only reduces the onset pyrolysis temperature of LS and enhances the decomposition of its primary constituents (hemicellulose, cellulose, proteins, lipids, and lignin) but also promotes condensation and cross-linking, leading to the formation of thermally stable char. Kinetic analysis via the Coats-Redfern method delineates three sub-stages for LS pyrolysis, with activation energies (Ea) of 62.9, 181.5, and 234.4 kJ/mol, respectively. The addition of KOH substantially reduces these energy barriers, with Ea values of 135.7, 127.5, and 51.8 kJ/mol across the corresponding stages, confirming its promoting effect in decomposing hemicellulose, cellulose, proteins, lipids, and particularly lignin. Analysis by Py-GC/MS and TG-FTIR shows that LS pyrolysis primarily generates oxygenated at 200-600 C and nitrogen-containing compounds (48.17%) at 800 C. In contrast, KOH addition dramatically intensifies decarboxylation, advancing CO2 release to 300 C and elevating its yield to 92.02-95.23%, while completely suppressing nitrogen-containing species at 800 C. The proposed mechanism highlights the role of KOH in forming potassium salt intermediates, which facilitate decarboxylation, deamination, and cleavage of C-C/ether bonds. These findings provide a scientific basis for optimizing KOH-activated pyrolysis of LS to produce tailored biochar for environmental applications.

The cooling demand of buildings makes up a significant share of global energy consumption and carbon emissions. To address this challenge, Passive Daytime Radiative Cooling (PDRC) technology has developed into a promising solution for cooling buildings without the need for electrical input. However, existing radiative cooler faces the problem of poor adhesion strength, especially regarding inorganic nanoparticles, which limits their practical applications. Here, a white cement-based material incorporating alumina particles is proposed to overcome these challenges. The aluminum-cement composite coating is fabricated through a purely inorganic formulation system, which opens up the possibility of using the material in practical architectural applications. In the aluminum-cement composite coating design, the alumina nanoparticles act as sunlight scatterers and heat emitters, while the white cement particles embedded in the material act as a binder to provide build compatibility. This design enhances interfacial adhesion strength, solar reflectance, and mid-infrared emissivity. Specifically, the aluminum-cement composite coating exhibits 4B-level adhesion strength that outperforms other inorganic nanoparticle materials, while the cooling performance (achieving a temperature drop of 5.65 degrees C compared to commercial coatings with reflectivity exceeding 92 %) is comparable or superior to previous reports. Importantly, the cheap and readily available raw materials and simple preparation process of the aluminum-cement composite coating facilitates the practical application of PDRC technology in architectural scenarios.

The electrochemical CO2 reduction reaction (CO2RR) offers a promising route to sustainable fuels, but developing cost-effective catalysts with high activity and selectivity remains a key challenge. In addressing this challenge, single-atom catalysts (SACs) represent a highly promising approach, for which precise control over the atomic interface is key to optimizing catalytic properties. In this work, a sulfur, copper and nitrogen co-doped carbon (S-Cu-ZIF-8-900) single-atom catalyst is synthesized via a facile high-temperature pyrolysis protocol with Cu-ZIF-8 as the precursor and thiophene as S doping reagent. The AC-HAADF-STEM and XAFS analyses confirm the presence of single-atom Cu and S/N co-coordination environments in the S-Cu-ZIF-8-900 catalyst. Electrochemical evaluation demonstrates that the S-Cu-ZIF-8-900 catalyst exhibits superior catalytic performance towards CO2RR, with maximum FECO of 94.4 % at -0.42 V (vs. RHE). DFT calculations reveal that the presence of CuS1N3 sites in S-Cu-ZIF-8-900 lowers the energy barrier for forming the key *COOH intermediate to 0.927 eV. Furthermore, the CuS1N3 sites in S-Cu-ZIF-8-900 suppress the HER more effectively than the CuN4 sites in Cu-ZIF-8-900. The effect of pyrolysis temperature (denoted as T) on the physicochemical properties of the SCu-ZIF-8-T materials and their electrochemical CO2 reduction performance are studied. It is found that relatively lower pyrolysis temperature (900 degrees C) increases the content of pyridinic-N, the content of Cu-N, the content of CuS, and the content of carbon defect, thereby boosting the catalytic performance of S-Cu-ZIF-8-T materials. This work highlights the critical role of sulfur doping in modulating the electronic structure of Cu-N-C SACs and provides a key insight for the design of high-efficiency CO2RR catalysts.

This study explored the ecological risks related to bulk resource utilization of industrial solid waste slag from the Yuanyanghu Power Plant in the Ningdong Energy and Chemical Industry Base. Scanning electron microscopy, energy spectrum analysis, and X-ray diffraction were used to characterize and analyze the physical and chemical properties of the slag. The total amount, effective forms, and different occurrence forms of six heavy metals, including lead (Pb), chromium (Cr), nickel (Ni), copper (Cu), cadmium (Cd), and arsenic (As), were determined. The ecological and environmental risks of the heavy metals in the power plant slag were comprehensively evaluated using the potential ecological risk index method and risk assessment coding (RAC) method. The results show that: (1) The slag exhibited a porous microstructure characterized by high concentrations of calcium (36.27%). The mineral composition of the furnace bottom slag was mainly mullite and quartz, and the contents of available potassium and organic matter were abundant. (2) The total concentrations of the six heavy metals in the furnace bottom slag did not exceed the screening value for soil pollution risk in agricultural land. Pb, Cd, Cr, As, and Ni in the slag mainly existed in the form of residue (F5), with Ni and As in the exchangeable state (F1), accounting for 28.05% and 25.49%, respectively. (3) The potential ecological risk index method indicates that the total RI index of the six elements in the slag is at level II, with a moderate ecological hazard level. Among all the metals, Cd and As contribute most to ecological risk. The RAC evaluation results indicate that Ni and As have moderate risk, Cd, Cu, and Cr have low risk, and Pb is risk-free. Based on a comprehensive evaluation, Cd, Ni, and As elements in slag are the main potential pollutants. In large-scale resource utilization, it is necessary to monitor and strengthen ecological risk prevention and control regularly.

Combustion-generated soot remains a significant environmental and health concern, necessitating effective mitigation strategies. This study investigates the suppression of soot in acetylene diffusion flames through fuel flow oscillation, employing both experimental and numerical approaches. The effects of relative amplitude (A out) on soot production rates (R soot) and sound pressure level (SPL) were examined across a range of excitation frequencies (f from 25 to 1200 Hz), acetylene flow rates ( Q C 2 H 2 ) , and nozzle inner diameters (D in from 1.05 to 6 mm). Additionally, the formation of standing acoustic waves was analyzed to reduce energy consumption. Results indicate that R soot is minimally influenced by Q C 2 H 2 but is predominantly controlled by the ratio A out/D in. There exists an optimal f at which both R soot and SPL reach their minima when A out/D in ≤ 2 mm-1, highlighting the role of combustion-acoustic coupling. Notably, the SPL increases sharply with ignition intensification. When standing waves are established within the fuel delivery tube, R soot can be reduced by 96.7% with a remarkably low speaker power of only 1.4 mW. These findings demonstrate a promising, energy-efficient method for soot mitigation in combustion systems through controlled acoustic oscillations.

In this paper, the effect of AKE on soot produced by non-premixed combustion of acetylene in Rijke tubes of different sizes is investigated experimentally and theoretically. The findings reveal that the soot suppression efficiency rises in a linear manner as the AKE grows. Furthermore, the spatial variation of AKE within tubes of different lengths leads to corresponding variations in soot suppression performance. The steady acoustic excitation leads to an oscillation period of the flame that is the same as the acoustic wave period, and the flame oscillation process is observed by the superposition of the flame fronts over an oscillation period. Qualitative analysis of these superposition diagrams was used to determine the flame oscillation velocity, revealing a positive correlation between soot suppression efficiency and the flame oscillation velocity. At the same soot suppression efficiency, the flame oscillation velocity is greater at high frequencies. This is due to the fact that more AKE is required at high frequencies to induce an increase in the flame oscillation velocity, in order to achieve a soot suppression effect similar to that at low frequencies.

Biomass fuel holds great promise as a carbon-neutral and renewable energy source. Nevertheless, the pollution produced during its combustion poses a substantial challenge to the advancement of biomass fuels. For the first time, a forced acoustic oscillation was applied to the combustion of redwood pellets to investigate the efficiency of soot suppression. Results show that the flame produced by the combustion of redwood pellets exhibits a trend of gradually rising and then gradually falling, regardless of the presence of an acoustic oscillation. Additionally, the flame temperature is higher with the acoustic oscillation than without it. In this experiment, the maximum flame height without acoustic oscillation can reach 180 mm. Under acoustic oscillation at frequencies of 100 Hz and 150 Hz, the maximum flame height is approximately 100 mm, with soot suppression efficiency reaching up to 80 %. At a frequency of 100 Hz and acoustic energy of 0.012 W & sdot;s, soot suppression efficiency can reach 89.42 %. The combustion efficiency of redwood pellets without acoustic oscillation is 74.64 %. Under acoustic oscillation, the combustion efficiency increases gradually with acoustic pressure, but the maximum efficiency is only 79.12 %, indicating that acoustic oscillation improves combustion efficiency but cannot achieve complete combustion. Soot suppression efficiency can surpass 50 % when particle velocity fluctuations exceed 0.04 m/s. This study confirms that applying acoustic oscillations to the combustion flame of redwood pellets can effectively suppress soot formation and reduce pollution. This provides a new approach to the design of biomass burners.

As a type of renewable energy source, solid biofuels have received lots of attention. However, the combustion of solid biofuels releases large amount of soot, which greatly inhibit their application. Development of effective strategy for suppressing the soot emission from solid biofuel combustion is of great importance. In this work, a novel approach integrating acoustic and electric fields is proposed to effectively suppress soot emissions during redwood pellet combustion. The effects of experimental parameters, i.e., the vertical height between the electrodes (EH), applied voltage (E), current (I), acoustic frequency (f), acoustic pressure (A) and electric field intensity on soot suppression are systematically investigated. Results show that application of an electric field causes the flame tip to spread outward and reduces flame height, while the acoustic and electric fields further suppress flame height and enhance stability. Under a constant EH, flame temperature increases with voltage; with constant voltage, it first rises, then falls, and stabilizes as EH increases. The flame centerline temperature is higher, and upper-region temperature fluctuations are reduced under combined fields. Maximum suppression reaches 77 % under either field alone and up to 100 % under optimal acoustic and electric fields. The acoustic field does not alter the current-voltage characteristics. The acoustic and electric fields generate transverse acoustic oscillations and longitudinal ionic wind, which alter the trajectories of fuel and soot particles, enhance fuel-air mixing, and promote soot re-oxidation.

Nanofluid boiling heat transfer in microchannels has the advantages of small size and high heat transfer efficiency, and can meet the requirements of large heat load and high structural integration. In this paper, the enhanced heat transfer characteristics experiment of nanofluids under electro-magnetic co-excitation were studied on a microchannel boiling flow experimental platform. The generation, deformation and motion mechanism of bubbles in nanofluids under electro-magnetic co-excitation were studied by high-speed photography and numerical simulation, achieving microscopic visualization of nanofluids. The experiment shows that the small bubbles are affected by the electric field force and pass through the electrode wire, and perform regular lateral reciprocating motion between the two sides of the wall. This motion of the bubbles can not only strengthen the orderly disturbance inside the fluid, but also will not disrupt the heat transfer mechanism between various media, making the heat transfer enhancement and not chaotic. Magnetic excitation causes the nanoparticles to form a magnetic coupling structure along the direction of the magnetic field, the average strengthening effect increased to 29%. When the current is applied and the electromagnetic coupling field is formed, the heat transfer effect is improved by 36%.

Soot formation from incomplete hydrocarbon combustion poses significant challenges for emission control in propulsion systems. This study employed experimental and numerical methods to investigate the transition process of the acetylene diffusion flame from laminar to turbulent flows, with particular focus on the evolutions of the soot formation rate (ṁ soot), flame temperature (T), and sound pressure level (SPL). Results from different regimes indicate the following: (1) In the laminar state, ṁ soot increased linearly with Re, with a growth rate positively correlated with the tube diameter. (2) After entering the transitional state, ṁ soot decreased exponentially by over 95%; T gradually increased by 150 K; and both SPL and the standard deviation of T (σ T ) initially rose and then declined. (3) After entering the fully turbulent state, SPL increased again whereas σ T stabilized at 14. When Re was decreased from the critical value at the occurrence of lift-off, the lifted flame could be maintained within the fully turbulent region (named as the reverse lifted flame) and ended upon entering the transitional region. ṁ soot of the reverse lifted flame was about 2 to 3 times that of the attached flame, which was due to the enhanced O2 entrainment from the bottom of the flame.

In this research, ZIF-8-derived porous nitrogen-doped carbon materials (ZNCs) with adjustable pore width structures and N/O functional groups are prepared via low temperature carbonization with the help of different additives. By introducing different compounds (C9H6O6, C3H2N2, C16H32O2, C12H22O11, C2H4N4, C3H6N6, Na3PO4, Na2SO4, CH3COONa, KOH, Na2CO3, and KHCO3) during the pyrolysis process, it is feasible to modulate the BET specific surface area, pore structure, and content of different N/O species of ZNCs. The influence of pore size ranges and contents of different N/O species on the CO2 capture efficiency of ZNCs is investigated. A multiple linear regression equation is constructed with V0-10 & Aring;, V7-9 & Aring;, pyrrole-N content, COOH content, and O-H content as the independent variables, and CO2 capture performance of ZNCs as the dependent variable. The results show that V0-10 & Aring; serves as a critical determinant of CO2 capture performance under standard conditions (25 degrees C, 1 bar), with pyrrole-N content and O-H content playing a secondary role. Among all the samples, 2ZNC-KHCO3-600 has the most excellent CO2 capture efficiency, demonstrating adsorption capacities of 4.60 mmol g-1 at 25 degrees C and 6.55 mmol g-1 at 0 degrees C under 1 bar pressure. In addition, 2ZNC-KHCO3-600 exhibits remarkable CO2/N2 selectivity (38.2) and cycling stability. This study provides valuable insights into the development of nitrogen-doped porous carbon materials with excellent CO2 capture capacity, as well as new insights into the understanding of the determining factors influencing the CO2 capture ability of nitrogen-doped porous carbon.

Photooxidation of CH4 to value-added chemicals with high selectivity offers a promising pathway to drive the rational utilization of natural gas resources with renewable energy under mild conditions. However, owing to the poor chemoselectivity of reactive oxygen radical formation and consecutive side reactions of primary products, the synthesis of peroxide directly from CH4 oxidation remains challenging. Here, we report single-atom ruthenium oxide-doped ZnO as a highly selective photocatalyst for the aerobic oxidation of CH4 to CH3OOH. Under optimal conditions, the CH3OOH formation rate over Ru1Ox/ZnO reaches 321 μmol gcat-1 h-1 with a high selectivity of 90.9% under simulated solar irradiation. Mechanistic studies reveal that the selective generation of •OOH radicals via oxygen reduction and the ability to prevent secondary side reactions of CH3OOH are the main advantages of Ru1Ox/ZnO, accounting for the remarkable selectivity of CH3OOH from CH4. The single-atom Ru oxide/ZnO catalyst also exhibits remarkable chemoselectivity to alkyl hydroperoxide in the photocatalytic oxidation of low paraffins, which provides a solution to prepare value-added peroxide from a single-step oxidation of hydrocarbon substrates.

Herein, porous carbon materials rich in oxygen (O)-containing functional groups and with abundant micropores were synthesized by carbonizing lychee seeds activated with various activators at a relatively low temperature of 600 °C. The incorporation of potassium and sodium salts during activation effectively modulated both the surface O functionalities and the microporous structure of the resulting porous carbon materials. The influence of these characteristics on CO2 adsorption performance was systematically investigated. A multiple linear regression model was developed to evaluate the impact of key factors including cumulative pore volumes in the pore size range of 5-7 Å (V5-7 Å), 0-10 Å (V0-10 Å), and 0-20 Å (V0-20 Å), total pore volume (VT), and the contents of C=OOH and C-OH groups on the CO2 adsorption capacity of the carbon materials at 1 bar and 25 °C. Results revealed that the C=OOH content is the most significant factor affecting CO2 uptake, while C-OH content and V0-20 Å also play important secondary roles. Notably, the LS-KOH-600 sample exhibited a high CO2 adsorption capacity, reaching 5 mmol/g at 25 °C and 7.15 mmol/g at 0 °C (1 bar). Furthermore, LS-KOH-600 demonstrated excellent CO2/N2 selectivity (29.9) and good cyclic stability under simulated flue gas conditions.