High Adsorption Energy Research Articles

Efficient degradation of organic contaminants in aqueous media using oxygen vacancy-rich MnO catalyst via peroxymonosulfate activation

Understanding the role of oxygen vacancies (OVs) in endowing catalytic activity is important for the design of efficient catalysts for advanced oxidation processes. In this study, we prepared MnO catalysts with different amounts of OVs under an atmosphere of H2 (MnO-H) and N2 (MnO-N) and investigated their acetaminophen (ACE) degradation efficiency via peroxymonosulfate (PMS) activation. MnO-H exhibited the best degradation performance because of its numerous OVs, compared with that of MnO-N and the commercial MnO. Data analysis revealed that ACE degradation proceeded via electron transfer. Density functional theory calculations confirmed that compared with the other catalysts, MnO-H/PMS with more OVs had higher catalytic activity, higher adsorption energy, lower work function, and higher electron transformation. The MnO-H/PMS system was stable at pH 3.0–9.0 and showed good recyclability. We believe that our findings will provide deeper insights into the role of OVs and encourage the use of less toxic metal oxides as catalysts in the selective degradation of organic pollutants in water bodies.

WS2 nanosheets decorated multi-layered MXene based chemiresistive sensor for efficient detection and discrimination of NH3 and NO2

Unsatisfactory sensing performance in terms of lack of selectivity and cross-sensitivity to humid environment remains a challenging issue for Ti3C2Tx MXene-based sensors. In this direction, the present study investigates the WS2/MXene composite-based chemiresistive sensor, utilizing the synergistic benefits of active adsorption sites of WS2 nanosheets with large surface and high conductive platform of multi-layered MXene sheets. The different weight proportions of WS2 to MXene were synthesized and a sensor fabricated using 25 wt % WS2/MXene exhibited preeminent response of 3–29 % and 6.87–44 % within range of 0.1–5 ppm NH3 and 1–100 ppb NO2, respectively. More importantly, the opposite transient response curves were observed for NH3 (increase in resistance) and NO2 (decrease in resistance), which served as a basis for their discrimination. Further, density functional theory simulations were performed to better comprehend the gas detecting capabilities of material, showing the high adsorption energies of WS2/MXene surface towards NH3 and NO2. Moreover, the humidity cross-sensitivity studies with NH3 and NO2 were also taken, and the sensor showed high resilience to humidity. Finally, an LED sensing module was employed to further distinguish the detection of NH3 and NO2, which showed the possibility of practical application of dual sensing using single sensing material.

A binary-heteroatom doped 3D multimode carbonaceous hybrids for high performance quasi-solid-state sodium dual-ion batteries

Carbonaceous materials have drawn immense attention for electrode materials of dual-ion batteries. However, they are hindered by the limited capacity due to the volume expansion during electrolyte ions extraction and insertion in the electrode materials. Here, 3D multimode carbonaceous nanocomposite with the inherent nitrogen content (12.22%) and sulfur content (0.93%) was successfully prepared consisting of the 0D carbon nanosphere on the surface of 2D the reduced graphene oxide intercalating into 1D carbon fiber gallery. The 3DMC-NS delivers a high initial discharge capacity of 353.5 mA h g−1 as anode and 140.9 mAh g−1 as cathode at a current density of 0.1 A g−1 owning to unique structure and abundant structural defects which contribute to rapid ion transport kinetics during electrochemical reactions. The 3DMC-NS based quasi-solid-state sodium dual-ion batteries promotes a stable reversible capacity of about 73.2 mAh g−1 at the current density of 0.05 mA g−1, and a superior capacity retention of 89.6% at 0.5 A g−1 after 1000 cycles. These results in enhanced the specific capacity of 3DMC-NS as bi-functional electrode which is coincided by density functional theory calculations owing to high adsorption energy and low diffusion barrier of carries. This investigation will render a feasible fantastic structure design to enhance the reaction kinetics of electrolyte ions for advanced electrode materials and promote the development of quasi-solid-state sodium dual-ion batteries.

In situ interface oxidation-adsorption by ferrate (VI)/PMS self-excitation: Unique dual-reaction platform for phenylarsonic acid degradation and immobilization

In this study, we dexterously constructed a unique in situ interface oxidation–adsorption dual-reaction platform through the self-excitation of ferrate (Fe(VI))/peroxymonosulfate (PMS) for phenylarsonic acid (PAA) and inorganic As(V) removal. When the molar ratio of Fe(VI)/PMS was 1:2, 80% degradation of PAA could be achieved within 180 min and the apparent constant value of the reaction rate (kobs) would reach up to 0.185 min−1. 1O2 and Fe(IV) were the main active species for degradation of PAA in Fe(VI)/PMS reaction system. In addition, we explored the possible degradation intermediates and pathway of PAA. In situ Fe(III) oxides generated from Fe(VI) decomposition could adsorb arsenic pollutants through ligand exchange with inorganic As(V) through surface hydroxyl groups to form Fe-O-As bonds. The effect of coexisting anions on the removal performance of the system was investigated, and the results showed that the presence of PO43− and CO32− promoted the oxidative degradation of PAA owing to the activation of PMS by PO43− and CO32−, but Cl− can inhibit the PAA degradation through a free radical scavenging mechanism. PO43− and SiO32− affected the adsorption and removal of the released inorganic As(V) due to their competitive adsorption of in situ Fe(III) oxides. Density functional theory (DFT) calculations indicated an obvious electron transfer (1.83 e) between the in situ Fe(III) oxides and inorganic As(V) with a high adsorption energy of −10.30 eV. These results indicate that the combination of Fe(VI) and PMS can effectively control the total arsenic (total-As) in water bodies.

Density functional theory study of high-temperature CO2 adsorption by Li2ZrO3: Effect of typical flue gas components on adsorption energy and electronic properties

Lithium zirconate (Li2ZrO3) is one of the best-performing high-temperature CO2 adsorbents, but the effect of flue gas on its mutual mechanism of action is not clear. The adsorption mechanism of CO2 and flue gas components on the Li2ZrO3 (111) surface is investigated theoretically through density functional theory (DFT), where the selected flue gas components are O2, H2O, and SO2. Theoretical calculations show that O2 exhibits physical adsorption and CO2, H2O, and SO2 exhibit chemisorption on the Li2ZrO3 surface. The energy potential barrier for CO2 adsorption on the Li2ZrO3(111) surface is 0.3 eV. CO2 is gradually desorbed at temperatures above 870 K. When there are flue gas atmospheres present, the desorption temperature of CO2 decreases, to a certain extent. All selected flue gas components inhibit the adsorption of CO2, O2, and H2O, weakening the interaction forces between the surface and CO2 and making it less stable. SO2 has the same adsorption sites as CO2, while SO2 has much higher adsorption energy than CO2. SO2 is more likely to adsorb onto and occupy the active sites of CO2.

Strong CO2 adsorption in narrow-pore ADOR zeolites: A combined experimental and computational study on IPC-12 and related structures

The ADOR method of synthesizing new zeolites has yielded a range of innovative siliceous materials featuring narrow pores, which facilitate relatively strong CO2 binding. This combined experimental and computational study investigates the adsorption properties of known ADOR materials (isoreticular zeolites of the UTL family and zeolites synthesized from UOV, *CTH, IWR, and IWW parent materials), as well as hypothetical ADOR zeolites derived from UOV, IWR, and IWW. The adsorption heat of carbon dioxide on the investigated ADOR materials was ascertained through i) a series of isotherms measured at 278–318 K and ii) Monte Carlo simulations at 300 K utilizing the DFT/CC technique. Consistently higher heats of CO2 adsorption found in -D4R materials (double four-membered ring interlayer linker removed from a parent zeolite) indicate stronger dispersion interactions compared to their -S4R counterparts (single four-membered ring removed). Among ADOR zeolites, IPC-12 (UOV-D4R) was identified as a zeolite possessing the strongest CO2 binding (heat of adsorption at the zero-coverage limit of 37.3 and 37.9 kJ/mol, as determined by experiment and theory, respectively). This high adsorption energy can be attributed to a distinct structural pattern featuring an elongated shape, which effectively accommodates CO2. Comparable structural patterns to IPC-12 were also detected in as-yet hypothetical ADOR products (IWR-D4R and IWW-D4R).

Magnetic ε-Phosphorene for Sensing Greenhouse Gas Molecules.

It is critical for gas sensors that sense greenhouse gas molecules to have both good sensitivity and selectivity for water molecules in the ambient environment. Here, we study the charge transfer, IV curves, and electric field tuning of vanadium-doped monolayer ϵ-phosphorene as a sensor for NO, NO2, and H2O gas molecules via first-principle and transport calculations. We find that the paramagnetic toxic molecules of NO and NO2 have a high adsorption energy on V-ϵ-phosphorene, which originates from a large amount of charge transfer driven by the hybridisation of the localised spin states of the host with the molecular frontier orbital. Using the non-equilibrium Green's function, we investigate the IV responses with respect to the adsorption of different molecules to study the performance of gas molecule sensors. Our IV curves show a larger amount of changes in resistance of the paramagnetic NO and NO2 than nonmagnetic H2O gas molecules, suggesting both sensitivity and selectivity. Moreover, our calculations show that an applied external electric field (gate voltage) can effectively tune the amount of charge transfer. More charge transfer makes the sensor more sensitive to the molecule, while less charge transfer can reduce the adsorption energy and remove the adsorbed molecules, allowing for the repeated use of the sensor.

Poisonous effect of carbon bearing species on adsorption of hydrogen on Pd-membrane surfaces

Hydrogen separation through Pd-membrane is one of the most promising technologies to produce pure H2. In this study, for the first time, the adsorption of hydrogen on covered Pd-membranes with both hydrogen and impurity gaseous species (CO, CO2 and CH4) was investigated using density functional theory (DFT). Specifically, the study aims to sample the energy landscape associated with hydrogen-adsorption while varying the structural and compositional degrees of freedom. The relative orientations of adsorbing molecule with respect to the surface of the slab, the crystallographic plane of the slab and various configurations of the adsorbed species have been investigated. In the case of compositional degrees of freedom, adsorption as a function of surface coverage, of hydrogen, is studied. The physisorption of H2 on Pd-surface at different coverages of H-atoms (and without any impurities) has revealed that among the available adsorption sites, top site with horizontally oriented gaseous molecule is energetically the most favorable (−0.343 eV). Among the impurity gaseous species, when investigated for their binding to the Pd-surface and for their effect on the physisorption energies of the H2, CO is found to alter the energetics of the adsorption process, indicating a higher poisoning effect relative to CO2 and CH4. Also, it has the highest adsorption energy (−1.887 eV). Moreover, the study also showed that at higher coverages of H-atoms, the physisorption energies of H2 decrease (−0.063 eV).

A novel copper oxide/titanium membrane integrated with peroxymonosulfate activation for efficient phenolic pollutants degradation

Herein, a novel CuO catalyst functionalized Ti-based catalytic membrane (FCTM) was prepared via the regulated electro-deposition technique followed with low-temperature calcination. The morphology of CuO catalyst and oxygen vacancy (OV) content can be controlled by adjusting the preparation conditions, under optimal condition (400 °C, electrolyte as sulfuric acid), the fern-shaped CuO catalyst was formed and the OV content was up to its highest level. Under the optimal treatment condition, the 4-chlorophenol (4-CP) removal of the membrane filtration combined with peroxymonosulfate (PMS) activation (MFPA) process was up to 98.2% (TOC removal of 88.2%). Mechanism studying showed that the enhanced performance in this system was mainly due to the increased production of singlet oxygen (1O2) via the co-effect of fern-shaped CuO (increased specific surface area) and its fine-tuned OV (precursor of 1O2), which not only synergistically enhanced adsorption ability but also offered more active sites for PMS activation. Theoretical calculations showed that the OV-rich CuO displayed high adsorption energy for PMS molecule, leading to the change in OO and OH bond (tend to 1O2) of the PMS molecule. Finally, the possible three degradation pathways of 4-CP were formed by the electrophilic attacking of 1O2.

A DFT study on the promising hydrogen storage performance of a light metal atom-decorated ZnO monolayer

The potential H2 adsorption/storage performance of the ZnO monolayer decorated with alkaline or alkaline earth metal atoms was studied using first-principle density functional theory (DFT) calculations. The light metal atom (Li, Na, K, Be, Mg, or Ca) could be atomically dispersed and decorated on the Zn–O hexatomic ring in the ZnO monolayer with high binding energy. Compared to Na-, K-, Be-, Mg-, or Ca-decorated ZnO, Li-decorated ZnO exhibited significantly stronger interactions with H2, resulting in higher adsorption energy, more transferred charges, and stronger orbital hybridizations. On the ZnO decorated with a single Li atom, four H2 molecules could be stored with an average adsorption energy of −0.242 eV. By increasing the two-sided Li coverage to one, three H2 molecules could still be stored on each decorated Li due to space limitations, with an acceptable average adsorption energy of −0.216 eV. As a result, the hydrogen storage capacity of the Li-decorated ZnO monolayer could be successfully and reasonably improved to 6.92 wt%. This study suggests that fully lithiated ZnO may have promising potential as an adsorbent for outstanding hydrogen storage performance.

The ability of zinc oxide nanostructures for removal of Pb2+, Cu2+, Ag2+ and Cd2+ ions from wastewater: computational perspective

In the heavy metal removal industry, adsorption is a famous and commonplace procedure well-recognized for its flexibility and utility. It is also a cost-effective procedure. Moreover, there are several adsorption procedures that are reversible on the one hand, and adsorbents may be reused after passing different desorption techniques on the other. The foundation of this research is to apply the calculations of the density functional theory (DFT) based on ab initio with an aim to explore the heavy metal atoms’ adsorption properties on ZnO–graphene resembling structure sheets and zinc oxide (ZnO) nanotubes. The heavy metals considered in this study include (Cu2+), (Pb2+), (Cd2+), and (Ag2+). In the initial stage, this study optimises both nanostructures. In the next phase, this study computes the steadiest configuration, the energy of adsorption, and the distance of equilibrium for each heavy metal with nanostructures utilising the mentioned DFT method. The findings were analyzed and compared. According to our case-by-case findings, ZnO-nanotubes exhibited better adsorption behaviour than ZnO–graphene sheets due to a smaller distance for equilibrium and higher adsorption energy. we’ve created the diagrams of the electronic density of states (DOS) in order to analyze the molecule adsorption electrical properties.

Ab initio study of metal-decorated carbon and silicon prismanes as the selective CO2 adsorbents

In this paper, we conducted comprehensive analysis of the selective adsorption of CO2 by carbon and silicon prismanes along with metal ions. The results of calculations from B3LYP/6-31G(d,p) and M06-2X/6-31G(d,p) levels of theory show that Be[Formula: see text], Mg[Formula: see text], Ca[Formula: see text] and Li[Formula: see text], Na[Formula: see text], K[Formula: see text] ions are bounded strongly enough to prismanes. The Be[Formula: see text] ion binds more strongly to the C8 H8 cubane with binding energy 9.66[Formula: see text]eV compared to Li[Formula: see text], Na[Formula: see text], K[Formula: see text], Mg[Formula: see text] and Ca[Formula: see text] ions having binding energies 1.26, 0.63, 0.51, 4.60 and 3.36[Formula: see text]eV, respectively. Similar results were obtained for larger prismanes C[Formula: see text]H[Formula: see text] and C[Formula: see text]H[Formula: see text]. Instead of binding energy, we determine the adsorption of gases on metal-ion prismane complex along with effect of temperature on different gas adsorption shows that C8H8_Mg[Formula: see text] and C8H8_Be[Formula: see text] are active adsorbents at temperatures above room temperature. It is also observed that in comparison to N2 and CH4, CO2 interacts more strongly with all prismanes decorated with metal ions. These non-covalent interaction plots are used to study the prismane and metal-ion interaction. Comparable study of silicon prismanes with M06 2X/6-31G (d, p) basis set, in terms of binding energy, adsorption of gases on prismane along with temperature effect, also possesses similar selectivity to CO2 molecule with even higher adsorption energies. Thus, beryllium-decorated prismanes can be considered as promising adsorbents of carbon dioxide with good selectivity and high adsorption energy.

Optimized geometric structure of Zn-BTC/POAP and Fe-BTC/POAP systems as electroactive materials in pseudocapacitors

In this work, Fe(II)-based metal organic framework (MOF), Zn-based MOF and hybrid poly orthoaminophenol/MOF composite were synthesized via a chemical method. Synthesized composite films have been characterized by conventional electrochemical methods and computational approach. The computational results show that both Zn-BTC and Fe-BTC interact well with 3POAP. Meanwhile, the adsorption energy of 3POAP on Fe-BTC is 2.03 eV higher than that of Zn-BTC. Therefore, it can be mentioned that the high adsorption energy of conductive polymer POAP on Fe-BTC compared to Zn-BTC has led to its better performance as the electrode of supercapacitors and these findings confirm the electrochemical results. It was found that in Zn-BTC/3POAP and Fe-BTC/3POAP systems the charge is transferred from the 3POAP to the MOFs. The results showed that the charge transfer from 3POAP to Fe-BTC is more than Zn-BTC which is a confirmation of the higher adsorption of 3POAP on Fe-BTC. The 3D periodic structure of Fe-BTC is generated by binuclear Fe(II) paddlewheel building units (PBUs) connected via the 1,3,5-benzenetricarboxylate organic ligands. Also, the adsorption energy of 3POAP on Fe2(PhCOO)4 and Zn2(PhCOO)4 was calculated using supermolecular approach. These results are compatible with the adsorption energy obtained from the periodic calculations, so that the adsorption of Fe structure was more than that of Zn. The Fe2(PhCOO)4…3POAP structure has the lowest band gap energy, so it can be concluded that the better adsorption of 3POAP on Fe-BTC not only results in higher adsorption energy, but also better electrical conductivity than the Zn-BTC. Computational results are in agreement with electrochemical results.

A theoretical study on the CO2-ODHP in HZSM-5 zeolite: From the perspective of adsorption and diffusion

The oxidative dehydrogenation of propane (ODHP) under the action of CO2 is receiving widespread attention. However, it has not been thoroughly studied in terms of adsorption and diffusion. So, the Monte Carlo and molecular dynamics simulations were used to study the adsorption/diffusion properties of the main reactants and products in HZSM-5. C3H8 has the highest adsorption energy and the lowest diffusivity, while the opposite is true for H2. And compared to C3H8, CO2 is more difficult to adsorb, but more diffuse. And the feed ratio has a significant effect on the overall reaction. When C3H8 is more than twice the amount of CO2, the adsorption efficiency of CO2 in the pores is very low. However, excess CO2 can also replace the adsorption of C3H8, reducing the efficiency of the reaction. The ratio of CO2 to C3H8 in the channel approaches 1:1 only when the feed ratio is around 1:3.

Enhanced photostability of multication lead halide perovskites through the use of azaadamantane-based modifiers

Complex lead halides incorporating simultaneously a few univalent cations such as cesium (Cs+), methylammonium (MA+) and formamidinium (FA+) represent highly promising materials for perovskite solar cells, delivering record-high power conversion efficiencies. Unfortunately, these materials demonstrate insufficient stability, which limits their practical implementation; therefore, improving the photochemical and thermal stability of multication lead halide perovskites is an urgent task that needs to be addressed to achieve sufficiently long operational lifetimes of perovskite solar cells to facilitate their commercial real-life applications. Herein, we present a comparative study of two azaadamantane-based molecular modifiers as stabilizing additives for Cs0.10MA0.15FA0.75PbI3 and Cs0.12FA0.88PbI3 perovskite formulations. An iodide of N-methylated 1,3,5,7-tetraazaadamantane known as urotropine (MAdI) showed a modest stabilizing effect in Cs0.10MA0.15FA0.75PbI3, though it stabilized effectively Cs0.12FA0.88PbI3. On the contrary, 4,6,10-trihydroxy-3,5,7-trimethyl-1,4,6,10-tetraazaadamantane hydrochloride (NAdCl) strongly enhanced the stability of both lead halide perovskites and prevented the formation of metallic lead Pb0 as a photolysis product. Different stabilizing effects caused by MAdI and NAdCl were related to their different localization within the perovskite films, as evidenced by nanoscale infrared (IR) s-SNOM microscopy. Density functional theory (DFT) calculations confirmed the enhanced stability granted by NAdCl by demonstrating a much higher adsorption energy towards undercoordinated lead atoms on the surface of the perovskite. Finally, the optimal molecular modification of Cs0.10MA0.15FA0.75PbI3 and Cs0.12FA0.88PbI3 films with azaadamantanes made them completely tolerant to light and heat within at least 5000 and 16 000 h of aging, thus setting new perovskite stability records and presenting the newly-developed material formulations as highly promising absorbers for efficient and stable perovskite solar cells.

Molecular Simulation of Methane Adsorption in Deep Shale Nanopores: Effect of Rock Constituents and Water

The molecular models of nanopores for major rock constituents in deep shale were constructed. The microscopic adsorption behavior of methane was simulated by coupling the grand canonical Monte Carlo and Molecular Dynamics methods and the effect of rock constituents was discussed. Based on the illite and kerogen nanopore models, the discrepancies in microscopic water distribution characteristics were elucidated, the effects of water on methane adsorption and its underlying mechanisms were revealed, and the competitive adsorption characteristics between water and methane were elaborated. The results show a similar trend in the microscopic distribution of methane between different shale rock constituents. Illite and kerogen slit pores have no significant difference in methane adsorption capacity. The adsorption capacity per unit mass of kerogen is greater than that of illite due to the smaller molar mass of the kerogen skeleton and its large intermolecular porosity. Illite has a greater affinity for water than methane. With increasing water content, water molecules preferentially occupy the high-energy adsorption sites and then overspread the entire pore walls to form water adsorption layers. Methane molecules are adsorbed on the water layers, and methane adsorption has little effect on water adsorption. Kerogen is characterized as mix-wetting. Water molecules are preferentially adsorbed on polar functional groups and gather around to form water clusters. In kerogen with high water content, methane adsorption can facilitate water cluster fusion and suppress water spreading along pore walls. In addition to adsorption, some water molecules dissolve in the kerogen matrix.

Insight into the role of SO2 on selenium conversion during adsorption by CaO: Theoretical calculation and experimental study

SO2 can noticeably impact the control of high toxic selenium emissions from flue gas by CaO. Surprisingly, our experiments showed that under certain conditions, SO2 can promote selenium capture by CaO, rather than hinder it. To elucidate the underlying mechanism, a combination of theoretical calculations and experiments was conducted. Thermodynamic equilibrium analysis revealed that gaseous SO2 and solid Ca-S reaction products can promote SeO2 converting to SeO/Se0. The Ca-S products facilitated greater SeO2 conversion compared to SO2. Experimental results demonstrated that selenium adsorption capacity of incompletely sulfurized CaO (CaO with pre-adsorbed SO2) was higher than that of completely sulfurized CaO (Ca-S products), highlighting the importance of adsorption sites of CaO. Density functional theory calculations showed that the pre-adsorbed SO2 hardly affected selenium adsorption energy on the SO2/CaO surface, while completely sulfurized CaO had low selenium adsorption energy, explaining the experimental phenomenon and proving necessary of CaO. Additionally, SeO/Se0 had higher adsorption energy on CaO than SeO2. Overall, the promotion of SO2 on selenium adsorption was primarily affected by two factors: 1) sulfur facilitating SeO2 conversion to SeO/Se0 which can be adsorbed more easily by CaO; 2) sufficient adsorption sites on CaO surface existing for SeO/Se0 adsorption, despite co-adsorption with sulfur.

Natural wood-derived charcoal embedded with bimetallic iron/cobalt sites to promote ciprofloxacin degradation

Structural design of high-performing catalysts for boosting refractory organic pollutants degradation remains a great challenge. Herein, a natural wood-derived catalyst comprising of wood carbon and Fe/Co sites was proposed as the peroxymonosulfate (PMS) activator to enhance ciprofloxacin (CIP) pollutant degradation. The bimetallic Fe/Co sites were highly dispersed and stabilized on carbon surface. The carbon-based catalyst achieved 100% removal rate for CIP within 4 min. After four consecutive cycles, the removal rate still reached 92.8%, displaying separable and reusable ability of this catalyst. The carbon-based catalyst could also exhibit excellent degradation performance under a wide pH range of 2.0–8.0. Density functional theory (DFT) calculation revealed that Fe/Co sites at wood carbon had the high adsorption energy and induced interfacial electron transfer for enhanced breakage of O–O bond. The sulfate radical (SO4•−), hydroxyl radical (•OH) and singlet oxygen (1O2) were main reactive oxygen species and their relative contribution was calculated to be 13.51%, 17.54% and 68.95%, respectively. The formed by-products and intermediates had almost no toxicity. This work proposes a new structural design of wood carbon-based system for enhancing antibiotic pollutant in aqueous environment, which facilitates the development of wastewater treatment technology.

Breaking interfacial charge transfer barrier by sulfite for efficient pollutants degradation: a case of BiVO4

Heterogeneous photocatalytic systems generally lack thermodynamic dependence on the degradation of organic pollutants in aqueous solution. Therefore, it is important to reveal the reasons for the inhibited surface kinetics but still be neglected. Herein, we reveal the mechanism that BiVO4 can’t degrade organics although it is thermodynamically feasible. The surface solvation and formation of double layer (compact layer and diffuse layer) makes low-polarity organics far away from the surface of BiVO4. We found that the introduction of sulfite can solve this problem. Theory calculation illustrates that sulfite can enter into the compact layer because of its higher adsorption energy on BiVO4 and lower adiabatic ionization potential (AIP). Then, photogenerated holes initiate the chain transformation of sulfite and produce strong oxidizing species which can diffuse out to degrade organics. This paper provides an insight into the understand the effects of solid-liquid interface on heterogeneously photocatalytic degradation of organic pollutants.

MXene modified anode of magnesium battery to improve the problems of voltage lag and irreversibility

As a kind of clean energy, magnesium batteries have become the main research direction of next-generation batteries. A long voltage lag time and irreversibility in aqueous electrolytes are problems faced by magnesium aqueous batteries. For the first time, we modified the anode of a magnesium aqueous battery with MXene. The modified battery not only reduced the voltage lag time of the battery but also improved the reversibility, cycle stability, and intermittent discharge performance of the magnesium aqueous battery. The calculation results of density functional theory showed that there is a high adsorption energy between MXene film and magnesium alloy. The calculation results of the ion diffusion energy barrier indicated that magnesium ions have a lower migration barrier on the surface of the MXene film layer. This research is of great significance to the development and application of magnesium batteries.