Ensuring the stability of cemented tailings backfill (CTB) in acid mine drainage (AMD) environments is essential for maintaining the safety of underground stopes. This study investigates the dynamic erosion behavior of CTB exposed to AMD, with a focus on the evolution of its mechanical properties and damage mechanisms over different erosion durations. Nuclear magnetic resonance (NMR) and water absorption tests were conducted to characterize the evolution of pore size distribution and connectivity, while acoustic emission (AE) monitoring technology was used to elucidate the fracture mechanism during deformation and failure. The results indicate that the porosity and the number of micropores in CTB initially decreased and then increased with prolonged erosion, whereas inter-pore connectivity remained relatively stable. AMD erosion significantly altered the stress-strain behavior of CTB. As erosion time increased, the average RA of AE signals showed a continuous upward trend, while the average AF exhibited the opposite trend. The proportion of tensile and shear microcracks changed systematically, and the dominant failure mode gradually shifted from tension-dominated to shear-dominated. At the early erosion stage, AE localization events were primarily low-energy and sparsely distributed, indicating limited damage. In the later stage, the number and energy of AE events increased, and their spatial distribution became concentrated in local stress concentration zones, signifying intensified damage. The deterioration of CTB in real AMD environments, characterized by strong acidity, high SO2-4 concentrations, and abundant solid particles, results from complex chemical reactions between cement hydration products and corrosive ions, as well as the physical blockage caused by solid particles. This study provides valuable insight into the long-term stability of CTB under AMD conditions and offers a theoretical foundation for safe mine design and the prevention of geological hazards.

Constructing metal single-atom-mediated Z-scheme charge transmission is a promising yet challenging avenue to realize efficient solar photocatalysis. Here, a single-atom Cu-bridged TiO2 hetero-phase assembly with opened cavities and Z-scheme charge transmission is fabricated via the illumination-assisted preparation recipe. When tested for gas-solid photocatalytic CO2 conversion, our photocatalyst displays an extraordinary activity with CH4 production rate reaching to 327.19 µmol·g-1·h-1, roughly 15.6 and 122.1 times enhancement than Degussa P25 TiO2 and TiO2(B), and it outperforms those of Cu nanoparticles, Pd single atoms, Pt nanoparticles, Pd nanoparticles, and Au nanoparticles-loaded counterparts as well as most TiO2-based composites ever reported. Based on the experimental test and theoretical calculation results, Cu single atoms act as the mediator to enhance interfacial charge transfer, which changes the photo-carrier transmission pathway from type-II to Z-scheme, accounting for the significant promotion of photocatalytic capability. The study results could propel the marked optimization of photocatalytic efficiency by steering Z-scheme charge transport with a single-atom mediator.

To provide a theoretical basis for optimizing the microstructure and mechanical properties of Co-based superalloy GH5188, the melting characteristic of VIM + ESR ingot, dissolution law of the carbides during homogenization, and the effect of homogenization treatment on mechanical properties have been investigated. The results show that incipient melting temperature of the ingot is 1260 1270 °C, and the low melting point phase is primary M23C6. In the homogenization process, the dissolution sequence of carbides was determined as follows: secondary M23C6 → primary M23C6 → primary M6C. Interestingly, lots of small blocky and rod-like W-rich carbides precipitated during the dissolution of primary M6C, but as the homogenization degree increased further, their precipitation was gradually inhibited. With the increasing homogenization time and temperature, the dendritic segregation reduced and the amount of residual carbides decreased gradually. The homogenization treatment of 1200 °C × 30h can completely dissolve the primary M23C6 and eliminate most of the small W-rich carbides, and the 1200 °C × 50h homogenization can eliminate majority of the carbides, minimize the segregation degrees of Cr, Co, and Ni, and significantly reduce that of W. Kinetic calculations indicate that the segregation of W can be completely eliminated after being homogenized at 1200 °C for about 59.3h. The room-temperature tensile properties of the alloy were not obviously influenced by the homogenization treatment. The high temperature hardness with homogenization treatment of 1200 °C × 50h was the greatest, while the high-temperature stress rupture life was the longest with the homogenization treatment of 1200 °C × 10h. This indicates that the prolonged homogenization processing time may not always bring beneficial effects.

The catalytic decomposition is one of the most efficient strategies for the ozone elimination. For ozone decomposition catalysts, the ability to accept or donate electrons often results in different rate-determining steps. In this study, we address this challenge by constructing a P-N heterojunction through integration of P-type (NiO) and N-type (TiO2) semiconductors. By leveraging the Fermi level disparity between them, the ration electron transfer at the interface was engineered to mitigate the limitation imposed by the rate-determining steps, thereby enhancing the activity and stability. A NiO-TiO2 catalyst was synthesized via a simple impregnation method. Characterization results demonstrated the electron transfer from NiO to TiO2 accelerated the decomposition of surface accumulated intermediate oxygen species, thereby mitigating the constraints of the rate-determining step. The optimized 10 % NiO-TiO2 catalyst maintained over 99 % conversion of 200 ppm ozone for 72 h at 30 degrees C under dry conditions with weight hourly space velocity (WHSV) = 1,000,000 mL/gcat & sdot;h. In contrast, a 10 % NiO-ZnO P-N heterojunction catalyst, designed with an inverted Fermi level alignment, showed drastically reduced activity, highlighting the crucial role of electron transfer direction in P-N heterojunction catalysts for ozone decomposition. This work provides valuable insights and strategies for designing stable and high-efficient catalysts for practical ozone decomposition.

Two-dimensional (2D) ultrathin nanosheet-based Z-scheme photocatalysts have sparked considerable interest for efficient solar fuel production, yet the relevant study for gas-solid photocatalytic CO2 conversion is still underdeveloped to now. Herein, ultrathin HNbO3 and TiO2(B) nanosheets were employed to construct the HNbO3TiO2(B) 2D-2D heterojunction with strengthened Z-scheme charge-separating capacity as confirmed by in-situ light-irradiated X-ray photoelectron spectroscopy, density functional theory calculation, and photoelectrochemical measurements. Moreover, the HNbO3-TiO2(B) junction possessed markedly improved CO2 adsorption and hydrophilicity than individual HNbO3 and TiO2(B), responsible for the former's superior CO2 photo-reduction capability. Noticeably, the CO2 photo-conversion activity of HNbO3-TiO2(B) was further promoted via site-preferred Au photo-deposition, with a CH4 generation rate as high as 53.75 mu mol g- 1h- 1 (selectivity of 82.9%), outperforming those of many TiO2-based photocatalysts reported previously. In addition, the HNbO3-TiO2(B)-Au hybrid possessed outstanding durability toward cyclic and long-term photocatalytic CO2 conversion. The strategy of integrating Z-scheme charge transmission and Schottky barrier in ultrathin nanosheet-based semiconductor heterojunction could inspire new thinking to design high-performance photocatalysts for sustainable energy access and environmental protection.

Since both can be obtained from renewable sources, ammonia and dimethyl ether (DME) emerge as one of the most promising fuel combination candidates. In this study, NH3/DME oxidation experiments were conducted within a jet stirred reactor (JSR) across various operation conditions to reveal kinetics of NH3/DME co-combustion. A detailed chemical mechanism was proposed to reasonably reproduce the measurements. The experimental results underscore the significant enhancement of DME on NH3 oxidation, where a notable decline in the initial oxidation temperature of NH3 was observed as the blending ratio of DME increased. At lean and stoichiometric conditions, NO concentration maintained a high level, exhibiting a consistent upward trend as the temperature progressively rose. The low NH3/high DME blending conditions are more liable to lead to the conversion of NH3 to NO. Whereas at rich conditions, the NO formation was inhibited. Moreover, the simulation results show that our proposed model could provide accurate predictions on the concentrations of NH3, O2, CO2 and CO, but underestimate the rates of NO formation reactions. Overall, the present model has better prediction performances on NH3/DME oxidation compared with the existing mechanism in the literatures. According to the sensitivity analysis, it is found that CH3OCH3(+M)=CH3+CH3O(+M) and H+O2=O+OH are the major reactions that trigger production of OH and HO2 active radicals, which promote the NH3 oxidation reaction and the formation of NO further. While the chain termination reactions NH2+NO=N2+H2O and CH3+HO2=CH4+O2 inhibit the reactivity. The HNO pathway dominates the formation of NO. With the escalation in the blending ratio of DME, the HNO pathway is strengthened, thereby causing a higher NO conversion. Above all, this research offers valuable insights into the oxidation mechanisms of NH3/DME and provides reliable empirical data sources for model construction and optimization.

The poor stability of organic-inorganic perovskite solar cells (PSCs) is commonly ascribed to elevated ion migration due to the low electronegativity of iodine. To address this issue, boric acid (BA) was chosen as a stabilizer for perovskite thin films. As a Lewis acid, the boric acid has an sp2 hybridized boron atom, which can readily accept a pair of electrons from the iodine ion in its vacant unhybridized p orbital, and the formation of the Pb-O bond further increases the iodide migration barrier. The significantly increased barrier of the iodine ion migration was demonstrated by the improved phase stability of the perovskite film under an electric field and the obviously enhanced stability of the perovskite films under strong ultraviolet light. The inclusion of the BA stabilizer in PSCs resulted in an enhanced power conversion efficiency (PCE) of 25.52 %. The initial efficiency of the BA-modified device was remained at 80 % after 1000 hours at 85 degrees C under around 30 % relative humidity (RH). When subjected to maximum power point tracking and 20-25 % RH, the PCE of BA-modified devices maintained an initial efficiency of 80 % after 1500 hours.

This study shows how to create layered nanosheet structures of Fe-doped Ni2P@CeO2 on nickel foam using hydrothermal synthesis and low-temperature phosphating for reliable and effective water splitting (HER and OER). The overpotential of the synthesized Fe-Ni2P@CeO2/NF is around 63 mV for the hydrogen evolution reaction (HER) and around 180 mV for the oxygen evolution reaction (OER) at a current density of 10 mA cm-2. Simultaneously, the distinctive stacked nanosheet architecture of Fe-Ni2P@CeO2/NF ensures that the catalyst maintains its effectiveness even after prolonged electrolysis (200 h) at a current density of 10 mA cm-2. Utilizing Fe-Ni2P@CeO2/NF as electrodes for both the HER and OER demonstrates that a potential of merely 1.47 V is sufficient to reach a current density of 10 mA cm-2, showcasing remarkable durability. Subsequent investigations indicate that the extraordinary efficacy of Fe-Ni2P@CeO2/NF can be attributed to its distinctive micromorphology, which enhances the exposure of active sites. Introducing Fe ions facilitates the formation of highly active trivalent nickel ions throughout the catalytic process. Additionally, the presence of both Ce3+ and Ce4+ encourages the catalyst to generate oxygen vacancies, thereby expediting electron transfer. Furthermore, DFT studies have shown that creating the catalyst's surface helps speed up the movement of electrons between the two phases and lowers the energy needed to produce H2 and O2.

Mercury in the coal-fired flue gas will cause severe damage to CO2 compression/purification equipment, and it must be seriously treated. Cold oxidation adsorption process (COAP) is a novel approach that has achieved the near-zero emission of major pollutants (SO2, NOx) from coal-fired flue gas. In this study, the removal of mercury at ultra-low temperatures (below 0 degrees C) within the scenario of COAP was investigated. As the adsorption temperature decreased (from 150 degrees C to -30 degrees C), the mercury removal efficiency of activated carbon initially increased and then decreased, peaking at -20 degrees C. A direct condensation phenomenon of mercury was discovered at -30 degrees C. The oxidation and adsorption process of NO was greatly accelerated at subzero temperatures, which enhanced mercury removal more effectively than at 150 degrees C. However, the homogeneous oxidation rates of Hg-O2 and HgHCl decreased at low temperatures. The Hg-TPD experiments confirmed that physical adsorption state of mercury predominated at low temperatures, with a small amount of condensed mercury also presented. A large amount of sulphate on used AC facilitated the conversion of physically adsorbed mercury into HgSO4. This study revealed the performance and mechanisms of mercury removal at ultra-low temperatures, which could provide theoretical guidance for the development of high-efficiency mercury removal in COAP technology.

Two-terminal monolithic perovskite/silicon tandem solar cells demonstrate huge advantages in power conversion efficiency compared with their respective single-junction counterparts1,2. However, suppressing interfacial recombination at the wide-bandgap perovskite/electron transport layer interface, without compromising its superior charge transport performance, remains a substantial challenge for perovskite/silicon tandem cells3,4. By exploiting the nanoscale discretely distributed lithium fluoride ultrathin layer followed by an additional deposition of diammonium diiodide molecule, we have devised a bilayer-intertwined passivation strategy that combines efficient electron extraction with further suppression of non-radiative recombination. We constructed perovskite/silicon tandem devices on a double-textured Czochralski-based silicon heterojunction cell, which featured a mildly textured front surface and a heavily textured rear surface, leading to simultaneously enhanced photocurrent and uncompromised rear passivation. The resulting perovskite/silicon tandem achieved an independently certified stabilized power conversion efficiency of 33.89%, accompanied by an impressive fill factor of 83.0% and an open-circuit voltage of nearly 1.97 V. To the best of our knowledge, this represents the first reported certified efficiency of a two-junction tandem solar cell exceeding the single-junction Shockley-Queisser limit of 33.7%.

The utilization of ammonia energy is plagued by NOx emissions. In this study, the fuel staging method was applied to reduce the NO emission of NH3/dimethyl ether (DME) co-combustion through the selective noncatalytic reduction (SNCR) process in the secondary stage. The effects of operating parameters on SNCR process were studied in the temperature range of 850-1150 degrees C. It was found that the NO removal efficiency first increased and then decreased with the rise of temperature. When phi pri = 0.9 and phi pri = 0.75, the optimum reaction temperature appeared at 950 degrees C and 900 degrees C, respectively. The NO removal efficiency increased with the increase of residence time and secondary NH3 injections. The NH3 slip was serious at low temperature. When the temperature exceeded 950 degrees C, NH3 emission decreased dramatically due to the oxidation of NH3. The modeling study was performed to simulate the experimental data using three mechanisms. The simulation results reproduced the evolution trend of NO, but it could not predict well the NO concentrations. These mechanisms overestimated the reaction rates of the NH2 + NO branching and failed to capture the early oxidation behavior of NH3. Further efforts should be made in NH3 chemistry to improve the reliability of the chemical mechanisms.

Nitrogen oxides are inevitable hazardous components in coal-fired flue gas. This study designed a series of experiments and combined theoretical calculations to systematically investigate the effect of NOx on the removal of element mercury (Hg-0) by nano-amorphous selenium (nano-a-Se). It was found that the impact of NOx on the removal of Hg-0 by nano-a-Se primarily involves two mechanisms: competitive adsorption between NOx and Hg-0, and the induced reduction effect of NOx on chemisorbed mercury (HgSe). NO inhibits the removal of Hg-0 by nano-a-Se, and competitive adsorption is identified as the main influencing factor. Whereas the inhibitory effect of NO2 on the adsorption of Hg-0 by nano a-Se can be counteracted due to its oxidizing effect on Hg-0. Therefore, although NO2 presents stronger competitiveness than NO in the competitive adsorption with Hg-0, it still shows a promoting effect on Hg-0 removal, with 50 ppm NO2 restoring 5.7 % of the Hg-0 removal efficiency. Additionally, the mechanism of NOx-induced reduction of HgSe was investigated in detail. NO2 is more capable of inducing the reduction of Hg(II) from HgSe to Hg-0. This study presents new insights into the underlying influence mechanism, which could provide valuable references for the application of other selenium-based adsorbents.

Phototheranostics, which consists of photothermal therapy (PTT) and photodynamic therapy (PDT), has exhibited huge potential in preventing the development of cancer. Then, phototheranostics utilizing photoacoustic imaging (PAI) in the second near-infrared (NIR-II) region, combined with high photothermal conversion efficiency (PCE) and cytotoxic reactive oxygen species (ROS) generation. In this work, we designed and prepared a fused-ring acceptor-donor-acceptor (A-D-A) molecule structure named INPIC-4F NP, known for its strong NIR light absorption and hydrophobic properties. INPIC-4F NPs in aqueous solution behaved excellently with NIR-II and PAI ability with NIR absorption at 808 nm and its fluorescence peaked at similar to 1000 nm. With singlet oxygen in a quantum yield of 11%, INPIC-4F NPs showed potential for PDT ability. Moreover, INPIC-4F showed a PCE value of 83% under laser irradiation, which was obviously higher than that caused by photothermal agents, demonstrating an excellent PTT capacity. Combining previous and present results, INPIC-4F nanoparticles could improve the treatment effect for cancer through fluorescence imaging-guided photothermal and photodynamic synergistic therapy.

The selective catalytic reduction of NOx by CO (CO-SCR) is a viable method for simultaneously mitigating NOx and CO emissions in motor vehicle exhaust and industrial flue gases. Extensive research has been conducted on noble metal catalysts because of their superior catalytic activity and stability compared to non-noble metals. Noble metal catalysts demonstrate efficient NOx conversion and high selectivity for N-2. However, achieving high conversion, selectivity, and stability over a wide temperature range in the presence of excess O-2, H2O, and SO2 remains a significant challenge. This review summarizes recent advancements in CO-SCR over noble metal catalysts, providing insights for the development of CO-SCR catalysts. This paper first examines the reaction mechanisms of CO-SCR, followed by a discussion on the design and optimization strategies of noble metal catalysts, with a focus on composition and structural effects. This includes creating active metal sites, selecting appropriate supports, integrating catalytic additives, choosing monometallic nanoparticles, alloying, and using single-atom catalysts. Finally, remaining challenges and potential avenues for future research have been suggested. The discovery of negatively charged noble metal single-atom-site catalysts presents new research opportunities.

Improving the removal effect of selenium in wet flue gas desulfurization system is a key way to reduce the emission of selenium pollutants from coal-fired power plants. In order to clarify the removal mechanism of selenium pollutants in the desulfurization tower, it is necessary to obtain accurate selenium gas-phase diffusion coefficient. In this paper, molecular dynamics simulations were used to carry out theoretical calculations of gas-phase diffusion coefficients of SeO2 (the main form of selenium in coal combustion flue gas). The gas-phase diffusion coefficients of SeO2 in the range of 393 K-433 K were measured by a self-developed heavy metal gas diffusion coefficient testing device to verify the accuracy of the molecular dynamics calculations. Furthermore, the calculated gas-phase diffusion coefficients of SeO2 under typical binary and ternary components were obtained by correcting on the basis of Fuller's formula. Finally, a single-droplet absorption model for SeO2 was constructed and experiments were carried out to compare the effect of the gas-phase diffusion coefficient on the accuracy of the model calculations. The error of the model calculations was reduced from 8.09 % to 1.96 % after the correction. In this study, the gas-phase diffusion coefficient of SeO2 in the low-temperature range of coal-fired flue gas was obtained. This study can provide basic data for the development of selenium migration mechanism and control technology.

The application of iron oxalate (FeC2O4) as a new high-energy anode material for lithium-ion batteries is astricted by difficulty in obtaining 100 % anhydrous material and inhibitive role of crystal water on lithium storage. Herein, we fabricated the trepang-liked hydrated iron oxalate (FeC2O4.2 H2O) anode materials by combining with dual-states copper and investigated the special function of copper. Because of the differentiated distribution between C2O42- and oxalic acid complexes ([Fe(C2O4)x]-2(x-1) and [Cu(C2O4)x]-2(x-1)), the CuC2O4.xH2O nanosheets with compound state adsorb and imbed on surface of rod-like FeC2O4.2 H2O particles. Meanwhile, copper element with ion state can effectively doped into the crystal structure of FeC2O4.2 H2O, due to the similar three-dimensional crystal structure between transition metal oxalates. In virtue of the differentiated electrochemical behavior of crystal water for iron oxalate and copper oxalate, the copper derivatives (Cu, CuO, Cu2O et al.), formed by the reaction between CuC2O4.xH2O and Li+, exhibit high electrochemical activity and electrical conductivity, which can significantly enhance the lithium storage ability of dihydrate iron oxalate. Hence, hydrated iron oxalate combined with dual-states copper, suggests superior reversible capacity (-550 mAh g-1 at 0.1 A g-1) and stable long-term cycling performance (-520 mAh g-1 at 0.5 A g-1 after 200 cycles). This paper provides a novel opportunity to weaken the inhibitive role of crystal water on lithium storage and enhance the electrochemical properties of hydrous oxalate materials.

A series of synthetic graphite was fabricated through metal oxide catalytic graphitization using purified anthracite (TYC). The effects of graphitization temperature, catalyst type and its addition methods on structure and properties of graphite products were investigated through the methods of XRD, Raman spectra, SEM, TEM, FTIR and resistivity tester. Increasing graphitization temperature favors the enhancement of order and size of graphite microcrystals, graphitization degree, and conductivity of graphitized products. TiO2 exhibited the best catalytic effects in catalytic graphitization. Compared to directly graphitized TYC at 2800 degrees C (TYC-28), the graphite catalyzed by TiO2 added physically (TYC-28-TiO2) and added chemically (TYC-28-C-TiO2) demonstrated a 13.0 and 16.7% increase in graphitization degree, respectively. Meanwhile, chemical addition method (0.61 x 10(-4) Omegam) outperformed physical addition method (1.21 x 10(-4) Omegam) in improving the electrical conductivity of graphitized products. Moreover, at 2400 degrees C, TYC catalyzed by TiO2 added physically and added chemically presented a graphitization degree of 73.7 and 77.6%, respectively, both exceeding that of TYC-28 (70.7%). Therefore, metallic oxides can enhance the graphitization degree while lowering the required graphitization temperature. This method holds promise for cost-effective and energy-efficient production of high-conductivity graphitized anthracite for batteries, supercapacitors, conductive coatings, and conductive adhesives.

Fe(III) has been proved to be a more effective oxidant than dissolved oxygen at ambient temperature, however, the role of Fe(III) in pyrite acidic pressure oxidation was rarely discussed so far. In this paper, in-situ electrochemical investigation was performed using a flow-through autoclave system in acidic pressure oxidation environment. The results illustrated that increasing Fe(III) concentrations led to raising in redox potential of the solution, and decreased passivation of pyrite caused by deposition of elemental sulfur. Reduction of Fe(III) at pyrite surface was a fast reaction with low activation energy, it was only slightly promoted by rising temperatures. While, the oxidation rate of pyrite at all investigated Fe(III) concentrations increased obviously with rising temperatures, the anodic reaction was the rate-limiting step in the overall reaction. Activation energy of pyrite oxidation decreased from 47.74 to 28.79 kJ/mol when Fe(III) concentration was increased from 0.05 to 0.50 g/L, showing that the reaction kinetics were limited by the rate of electrochemical reaction at low Fe(III) concentrations, while, it gradually turned to be diffusion control with increasing Fe(III) concentrations.

The selective catalytic reduction (SCR) of NOx, utilizing carbon monoxide (CO) and ammonia (NH3), is recognized as an effective approach for NOx abatement. During the SCR process, the appropriate pretreatment of catalysts can significantly enhance their surface and interfacial structures, thereby improving their activity, selectivity, and stability. This review begins with the reaction mechanisms of CO-SCR and NH3-SCR, followed by an introduction to various pretreatment strategies that can enhance the performance of catalysts employed in these two reactions. An in-depth discussion is provided regarding how different pretreatment methods influence the active structure of catalysts, the key steps of the reactions, and the overall catalytic performance. Subsequently, a comparative analysis of the pretreatment strategies employed for both reactions is presented, highlighting their similarities and differences, thereby elucidating the essence of pretreatment techniques. Lastly, the paper identifies the current challenges encountered in the field of pretreatment and proposes potential directions for future development. This work aims to offer theoretical insights that may inspire innovative pretreatment strategies in CO-SCR and NH3-SCR among researchers and engineers.

The selective catalytic reduction of NO by CO (CO-SCR) is regarded as a highly promising technology for the purification of industrial exhaust gas due to its ability to simultaneously eliminate two toxic and harmful gases. This review provides an overview of recent advances in the CO-SCR reaction, firstly exploring the multiple reaction pathways for the reduction of NO to N2 by CO, and then analyzing in depth the multidimensional influence mechanisms of O2, SO2 and H2O on this reaction. In addition, the structural control strategies to improve the resistance of noble- and non-precious metal-based single-atom and cluster catalysts to O2, SO2 and H2O were discussed from the perspectives of particle size regulation, electronic structure control, and surface/interfacial structure modulation. Finally, the paper summarizes the current challenges of CO-SCR technology and provides detailed suggestions for future research directions, with the objective of enriching the design concepts for high-efficiency denitrification catalysts.