XPS Analysis Research Articles

Growth mechanism and the properties of CIGS thin films for zero bias photodetector devices

CuInGaSe2 quaternary thin films have been deposited using a single-source, single-step thermal evaporation technique using hydrothermally fabricated CIGS powder. Highly crystalline, homogeneous, and stoichiometric CIGS powder source was prepared by a hydrothermal method and then evaporated at substrate temperatures of room temperature, 150°C, and 300°C. The bulk and surface structural, morphological, and optical properties of the samples were analyzed. The sample deposited at room temperature did not show any phase formation; however, increasing the substrate temperature resulted in the formation of binary and quaternary phases due to interdiffusion of the species. XPS and Raman spectra analysis revealed nanocrystalline Cu2Se phase formation at the interface, while the bulk of the sample remained single-phase CIGS. A higher deposition temperature also facilitated larger grain size and a more compact surface morphology. Increasing the substrate temperature increased the likelihood of interdiffusion of the species from the evaporation flux and controlled the bulk and surface properties of the samples. CIGS/CdS active photodetectors were fabricated by deposition of a CdS buffer layer, with the sample deposited at 150°C showing the highest photocurrent along with low response and recovery times at 0 V bias.

Research on the Corrosion Inhibition Behavior and Mechanism of 1-Hydroxy-1,1-ethyledine Disodium Phosphonate under an Iron Bacteria System

Regenerated water serves as a supplementary source for circulating cooling water systems, but it often fosters microbial growth within pipelines. Given its widespread use as a corrosion inhibitor, understanding HEDP’s efficacy in microbial environments and its impact on microorganisms is imperative. This study established an iron bacterial system by isolating and enriching iron bacteria. Through a comprehensive approach incorporating corrosion weight loss analysis, XPS analysis, SEM electron microscopy, as well as microbial and electrochemical testing, the corrosion inhibition behavior and mechanism of HEDP within the iron bacterial system were investigated. The findings reveal that within the iron bacterial system, HEDP achieves a corrosion inhibition rate of 76% following four distinct stages—weakening, strengthening, stabilizing, and further strengthening—underscoring its robust corrosion inhibition capability. Moreover, HEDP enhances the density of biofilms and elevates the activation energy of carbon steel interfaces. It alternates with oxygen to continuously suppress the activity of IRB while gradually inhibiting the activity of IOB. This process culminates in a corrosion inhibition mechanism where cathodic inhibition predominates, supported by anodic inhibition as a complementary mechanism.

Ligand mediated self-assembly of cobalt nanoclusters for tunable supercapacitors

Self-assembly of thiolated cobalt-based nanoclusters was achieved by a simple and one-step synthesis process towards the development of a tunable hybrid supercapacitor. Here, we report the wet chemical synthesis of self-assembly of cobalt nanoclusters (CoNCs) using three different thiols namely glutathione (GS), 3-mercapto propyl sulfonate (MPS) and 3-mercapto propionic acid (MPA) protected individually. The variation in the capping ability of the thiolate ligands brings the proximal changes in the optical, structural and electrochemical properties. In CoNCs, the structural and morphological changes that evolved from the obtained GS-CoNCs, MPS-CoNCs, and MPA-CoNCs were confirmed using UV–vis spectroscopy, XRD, and TEM analysis. The stability of CoNCs and binding states of cobalt metal were determined using TG and XPS analysis respectively. The divergence in the rigidifying nature of various thiolated cobalt nanoclusters significantly influences their capacitance ability for energy storage via altering the porosity and electron transfer characteristics. The rigid dense multifunctional ligands like GS facilitate the electron-hole hopping process in the nano-pockets available in GS, which enhances the energy storage capability and diffusion among ligand-metal-ligand chains. Wherein, the other two ligands MPS and MPA show comparatively lower supercapacitance activities due to diverse functionality and rigidify. The charge-discharge studies explore the supercapacitor behaviour of GS, MPS and MPA-protected CoNCs with the specific capacitance of 540, 494 and 358 F g−1 respectively at the current density of 1 A g−1.

Cascaded *CO-*COH Intermediates on a Nonmetallic Plasmonic Photocatalyst for CO2-to-C2H6 with 90.6% Selectivity.

Oxygen vacancies (OV) in nonmetallic plasmonic photocatalysts can decrease the energy barrier for CO2 reduction, boosting C1 intermediate production for potential C2 formation. However, their susceptibility to oxidation weakens C1 intermediate adsorption. Herein we proposed a "photoelectron injection" strategy to safeguard OV in W18O49 by creating a W18O49/ZIS (W/Z) plasmonic photocatalyst. Moreover, photoelectrons contribute to the local multi-electron environment of W18O49, enhancing the intrinsic excitation of its hot electrons with extended lifetimes, as confirmed by in-situ XPS and femtosecond transient absorption analysis. Density functional theory calculations revealed that W/Z with Ov enhances CO2 adsorption, activating *CO production, while reducing the energy barrier for *COH production (0.054 eV) and subsequent *CO-COH coupling (0.574 eV). Successive hydrogenation revealed that the free energy for *CH2CH2 hydrogenation (0.108 eV) was lower than that for *CH2CH2 desorption for C2H4 production (0.277 eV), favouring C2H6 production. Consequently, W/Z achieves an efficient C2H6 activity of 653.6 μmol g-1 h-1 under visible light, with an exceptionally high selectivity of 90.6%. This work offers a new strategy for the rational design of plasmonic photocatalysts with high selectivity for C2+ products.

Cascaded *CO‐*COH Intermediates on a Nonmetallic Plasmonic Photocatalyst for CO2‐to‐C2H6 with 90.6% Selectivity

Oxygen vacancies (OV) in nonmetallic plasmonic photocatalysts can decrease the energy barrier for CO2 reduction, boosting C1 intermediate production for potential C2 formation. However, their susceptibility to oxidation weakens C1 intermediate adsorption. Herein we proposed a "photoelectron injection" strategy to safeguard OV in W18O49 by creating a W18O49/ZIS (W/Z) plasmonic photocatalyst. Moreover, photoelectrons contribute to the local multi‐electron environment of W18O49, enhancing the intrinsic excitation of its hot electrons with extended lifetimes, as confirmed by in‐situ XPS and femtosecond transient absorption analysis. Density functional theory calculations revealed that W/Z with Ov enhances CO2 adsorption, activating *CO production, while reducing the energy barrier for *COH production (0.054 eV) and subsequent *CO‐COH coupling (0.574 eV). Successive hydrogenation revealed that the free energy for *CH2CH2 hydrogenation (0.108 eV) was lower than that for *CH2CH2 desorption for C2H4 production (0.277 eV), favouring C2H6 production. Consequently, W/Z achieves an efficient C2H6 activity of 653.6 μmol g‐1 h‐1 under visible light, with an exceptionally high selectivity of 90.6%. This work offers a new strategy for the rational design of plasmonic photocatalysts with high selectivity for C2+ products.

Enhanced simultaneous phosphate recovery and organics removal by a nucleation crystallization pelleting process

Naturally co-occurring phosphate (P) and dissolved organic matter (DOM) in raised livestock wastewater have caused increasing public concerns. This study fabricated a novel nucleation crystallization pelleting process (NCP) showing orientated P recovery and HA (as a major fraction of DOM) removal from wastewater. Results showed that after 120 h of continuous operation, the total removal efficiency of P and HA stabilized at 97.5 % and 92 %, respectively, by using a three-stage NCP process. The NCP results further demonstrated that the main recovery mechanism of P involves surface-induced precipitation of P in the form of hydroxyapatite (HAP) on the seed surface by modulating the supersaturation of HAP in the system. The FTIR, SEM-EDS, and XPS analysis combined with DFT calculations revealed the molecular-level mechanisms for removing HA, which were mainly controlled by Calcium ions bridging, H-bonding, and π-π stacking. More importantly, the attached HAP on the seed surface would enhance the mutual interaction with HA, further enhancing the removal efficiency of HA. This contribution not only opens a high potential avenue for further research on the simultaneous capture of P and organic matter but also sheds light on the development of the practical application of the NCP remediation strategies.

A synthesis of styrene-grafted starch accompanied with reaction condition optimization and microstructural and macroscopic property analysis

Styrene grafting is efficient to alter starch macroscopic property. Nevertheless, reaction mechanism, condition and products structure and properties are blurry. A deep exploration is necessary. Herein, K2S2O8 and styrene were chosen for corn starch modification. Reaction conditions involving K2S2O8 and styrene amounts, temperature and period were explored. Concurrently, microstructural and macroscopic properties of modified starches were explored via FT-IR, XPS, 13C NMR, GPC, XRD, SEM, TGA, DSC, CA and water dispersibility analysis. Main results reveal that K2S2O8 and styrene amounts, temperature and period as 3 and 200 wt%, 50 °C and 3 h is an optimized condition for starch grafting styrene, achieving a grafting yield (GY) as 45.8 wt%. GPC, XPS and 13C NMR analysis certified successful grafting and grafting mainly occurred at C-3 site OH within glucose unit. This variation converted starch crystalline shape transformation from A-typed to V-typed accompanied with crystallinity, thermal-stability and swelling characteristic decrease and surface hydrophobicity elevation. With GY increased from 0 to 45.8 wt% crystallinity decreased from 38.7 to 15.1%, thermal-decomposition temperature decreased by 10 °C, gelatinization temperature and CA increased by 50 °C and 70°, respectively. It seems a small amount styrene grafting can alter starch macroscopic property such as hydrophilicity efficiently, readily to manufacture hydrophobic starch. This hydrophobic starch might have a potential use in plastic industry, enlarging starch use application, meaningful.

Cation Modulation in AgSbTe2 Realizes Carrier Optimization, Defect Engineering, and a 7% Single-Leg Thermoelectric Efficiency.

AgSbTe2 plays a pivotal role in mid-temperature thermoelectric generators (TEGs). Leveraging the seminal advances in cation manipulation within AgSbTe2, this study demonstrates an enhanced TE power factor (PF=S2σ) of 1.5mWm-1K-2 and a peak zT of 1.5 at 583K in an off-stoichiometric Ag1.04Sb0.96Te2 crystal. The introduction of Ge in place of Ag leads to an increased nH as evidenced by the detection of trace Ge4+ through XPS analysis. Further chemical state analysis reveals the simultaneous presence of Ag+, Sb3+, and Ge4+, elucidating the effect of cation modulations. TEM characterizations validate the presence of superlattice structure, and the linear defects discerned within the AgSbTe2 matrix. Consequently, the lattice thermal conductivity κL is substantially reduced in the Ag1.02Ge0.02Sb0.96Te2 crystal, yielding a peak zT of 1.77 at 623K. This notable advancement is attributed to the counterbalance achieved between the enhanced PF and the reduced κL, facilitated by cation modulation. Additionally, a single-leg TE device incorporating Ag1.02Ge0.02Sb0.96Te2 demonstrates a conversion efficiency of 7% across a temperature gradient (ΔT) of 350K. This study corroborates the efficacy of cation modulation through thermodynamic approaches and establishes a relationship between transport properties and the presence of defects.

Influence of metal ions on cysteine as a corrosion inhibitor for low carbon steel in sulfuric acid: Polarization, EIS, XPS, and DFT analysis

This study examines the effectiveness of cysteine as an eco-friendly in inhibiting the corrosion of low-carbon steel in a sulfuric acid solution and the impact of adding various metal ions (Cu2+, Ni2+, and Co2+) to the media. All solutions were prepared using distilled water. The results show that 5 mM cysteine inhibits corrosion (IE = 65%), increasing to 93.5% in the presence of 4×10-5 M Cu2+ ions, but decreasing with the addition of Co2+ or Ni2+ ions. The inhibitive action of cysteine-Cu is the best one and that may be attributed to the formation of a protective coating on the metal surface, which prevents chemical reactions in an aggressive environment. Moreover, the DFT calculation found that the adsorption energy increased from −17.2 to −97.7 and −104.6 kcal/mol in the case of cysteine, Cysteine-Cu SAM, and Cysteine-Cu(II) Salt and the closest atom to the surface reduced from 2.576 to 2.128 and 2.146 Å which indicates Cysteine-Cu better adhere to the surface. SEM, XRD, and XPS were used to analyze the formation of the protective layer. This has the potential to develop new and more effective corrosion inhibitors for industrial applications.

A Phosphorylated Dendrimer-Supported Biomass-Derived Magnetic Nanoparticle Adsorbent for Efficient Uranium Removal.

A novel biomass-based magnetic nanoparticle (Fe3O4-P-CMC/PAMAM) was synthesized by crosslinking carboxymethyl chitosan (CMC) and poly(amidoamine) (PAMAM), followed by phosphorylation with the incorporation of magnetic ferric oxide nanoparticles. The characterization results verified the successful functionalization and structural integrity of the adsorbents with a surface area of ca. 43 m2/g. Batch adsorption experiments revealed that the adsorbent exhibited a maximum adsorption capacity of 1513.47 mg·g-1 for U(VI) at pH 5.5 and 298.15 K, with Fe3O4-P-CMC/G1.5-2 showing the highest affinity among the series. The adsorption kinetics adhered to a pseudo-second-order model (R2 = 0.99, qe,exp = 463.81 mg·g-1, k2 = 2.15×10-2 g·mg-1·min-1), indicating a chemically driven process. Thermodynamic analysis suggested that the adsorption was endothermic and spontaneous (ΔH° = 14.71 kJ·mol-1, ΔG° = -50.63 kJ·mol-1, 298. 15 K), with increasing adsorption capacity at higher temperatures. The adsorbent demonstrated significant selectivity for U(VI) in the presence of competing cations, with Fe3O4-P-CMC/G1.5-2 showing a high selectivity coefficient. The performed desorption and reusability tests indicated that the adsorbent could be effectively regenerated using 1M HCl, maintaining its adsorption capacity after five cycles. XPS analysis highlighted the role of phosphonate and amino groups in the complexation with uranyl ions, and validated the existence of bimodal U4f peaks at 380.1 eV and 390.1 eV belonging to U 4f7/2 and U 4f5/2. The results of this study underscore the promise of the developed adsorbent as an effective and selective material for the treatment of uranium-contaminated wastewater.

Effect of copper addition on passivation film of TC18 titanium alloy

TC18 and TC18–0.5Cu alloys were prepared by vacuum arc furnace melting. The properties of its passivation film in 5 % NaCl solution were investigated using constant potential polarization, electrochemical impedance spectroscopy, Mott-Schottky and XPS analysis. The corrosion resistance of TC18 passivation films was found to be superior to that of TC18–0.5Cu alloy. The passivation films formed on both alloys displayed n-type semiconductor behavior. In the TC18–0.5Cu alloy, the presence of copper as a form of copper interstitial segregation Cuix+ was observed, which was subsequently replaced by low-mobility titanium ionic vacancies in the form of a cationic sublattice CuTix′, as a small defect.

Aromatic‐rich oil production from catalytic co‐pyrolysis of pine sawdust and LDPE with bifunctional biochar by different preparation methods

AbstractBackgroundCatalytic co‐pyrolysis of biomass with waste plastics can produce high‐quality chemicals, making it a potential alternative to fossil fuels. The production of aromatic‐rich oil was achieved in this work by the catalytic co‐pyrolysis of pine sawdust and low‐density polyethylene (LDPE) using a series of biochar (BC) made using different preparation methods. Zinc chloride (ZnCl2) was employed to activate the BC during the preparation process, owing to its optimal activity for the co‐pyrolysis intermediates. The study compared the effects of BCs activated using different treatment methods on the yield and fractions of pine sawdust and LDPE co‐pyrolysis in a fast pyrolysis tube furnace at 650 °C.ResultsThe study indicates that the ZnCl2 BC, prepared from pine sawdust by fast pyrolysis (F‐AC), exhibited the best aromatic catalytic activity. The selectivity to aromatic hydrocarbons was 72.53%, and the content of BTEX (benzene, toluene, ethylbenzene, and xylene) was 32.17%.ConclusionThe Diels–Alder reaction and aromatization were made more effective due to the Zn sites and large pore structure in F‐AC. Using Fourier transform infrared, scanning electron microscopy and X‐ray photoelectron spectroscopy analysis, it was found that F‐AC contained more oxygen (O)‐containing groups in abundance, which improved its adsorption capacity for reaction intermediates. At the same time, the porous structure and high SSA of BC provided a region for the reaction intermediate to interact with the active center containing O‐containing groups. This enhanced the synergy between biomass and plastics and raised the selectivity of aromatic hydrocarbons. It provides a reference for the application of carbon‐based materials in the co‐pyrolysis of biomass and waste plastics. © 2024 Society of Chemical Industry (SCI).

Synergetic supercapattery: Stitching of cobalt zinc manganese oxide and polyaniline matrix for efficient energy storage applications

Optimizing energy storage performance requires the integration of both battery and supercapacitor advantages into a hybrid device. This study focuses on the strategic combination of positive (battery-like) and negative (electrical double layer, EDL) electrode materials in a single device, known as a supercapattery. Cobalt zinc manganese oxide (CZMO) ternary composite and polyaniline (PANI) are synthesized via hydrothermal and polymerization methods, respectively. The CZMO/PANI composite is prepared using a physical blending method. XRD and FTIR analyses confirmed the composition of CZMO/PANI, while surface morphological analysis (FESEM and HRTEM) demonstrated successful intercalation between CZMO nanorods and the PANI matrix. XPS and BET analyses are employed to examine the chemical composition and surface area of the composite. Electrochemical performance of CZMO, PANI, and CZMO/PANI is individually analyzed using a three-electrode system. It is evident that the CZMO/PANI composite exhibits a better specific capacity (340 C g−1) than CZMO and PANI. The two-electrode system (device), embodying CZMO/PANI as the positive electrode and activated carbon as the negative electrode, exhibits promising Specific energy 30.75 Wh kg−1 and specific power 820 W kg−1. Based on these results, it is evident that the CZMO/PANI composite will be a viable option for supercapattery applications.

Hemocompatibility and Preangiogenic Attributes of SiBxCyNzOm Coatings for Biomedical Applications.

In current clinical practices related to orthopedics, dental, and cardiovascular surgeries, a number of biomaterial coatings, such as hydroxyapatite (HAp), diamond-like carbon (DLC), have been used in combination with metallic substrates (stainless steel, Ti6Al4V alloy, etc.). Although SiBCN coatings are widely explored in material science for diverse applications, their potential remains largely unexplored for biomedical applications. With this motivation, the present work reports the development of SiBxCyNzOm coatings on a Ti6Al4V substrate, employing a reactive radiofrequency (RF) magnetron sputtering technique. Three different coating compositions (Si0.27B0.10C0.31N0.07O0.24, Si0.23B0.06C0.21N0.22O0.27, and Si0.20B0.05C0.19N0.20O0.35) were obtained using a Si2BC2N target and varying nitrogen flow rates. The hydrophilic properties of the as-synthesized coatings were rationalized in terms of an increase in the number of oxygen-containing functional groups (OH and NO) on the surface, as probed using XPS and FTIR analyses. Furthermore, the cellular monoculture of SVEC4-10 endothelial cells and L929 fibroblasts established good cytocompatibility. More importantly, the coculture system of SVEC4-10 and L929, in the absence of growth factors, demonstrated clear cellular phenotypical changes, with extensive sprouting leading to tube-like morphologies on the coating surfaces, when stimulated using a customized cell stimulator (StimuCell) with 1.15 V/cm direct current (DC) electric field strength for 1 h. In addition, the hemocompatibility assessment using human blood samples revealed clinically acceptable hemolysis, less erythrocyte adhesion, shorter plasma recalcification, and reduced risk for thrombosis on the SiBxCyNzOm coatings, when compared to uncoated Ti6Al4V. Taken together, the present study unambiguously establishes excellent cytocompatibility, hemocompatibility, and defines the preangiogenic properties of SiBxCyNzOm bioceramic coatings for potential biomedical applications.

Preparation of imprinted phenol gel with ultra-high adsorption capacity based on porous biochar: 5-stage tandem column, response surface method, and mechanism analysis

Wastewater from industries like petroleum refining and pharmaceuticals contains high levels of phenolic compounds. Discharging this untreated wastewater can severely pollute water bodies. To address this issue, a biochar-based composite imprinting phenol gel(MgNBC@MIP) was designed to effectively remove phenolic compounds and control phenol levels in water environments. The adjustment of the aromatic structure and pore architecture of the biochar effectively enhanced its affinity for phenolic compounds. Subsequently, the individual effects of factors such as pH, salt, and humic acid on adsorption were explored. Optimization of the adsorption process was carried out using a four-factor, three-level response surface method, yielding a theoretical formula for the adsorption amount, with a maximum adsorption capacity of 308.311 mg/g. Moreover, the adsorption of phenol and its derivatives by MgNBC@MIP followed the Langmuir isothermal model and the PSO kinetic model. A comprehensive mechanism analysis elaborated in detail on the diffusion and adsorption process of phenol from the aqueous phase to the adsorption site. Correlation FTIR and XPS analysis confirmed that π-π electron donor–acceptor interactions, hydrogen bonding, pore filling, and metal complexation were the primary driving forces for phenol adsorption. Significantly, MgNBC@MIP exhibited good reusability in the adsorption–desorption cycle. The design of a five-stage tandem column adsorption experiment opens up avenues for the industrial application of MgNBC@MIP.

Green synthesis of nZVI-modified biochar significantly enhanced the removal of Cr(VI) from aqueous solution.

Water contamination by hexavalent chromium (Cr(VI)) seriously jeopardizes human health, which is a pressing environmental concern. Biochar-loaded green-synthesized nZVI, as a green and environmentally friendly material, can efficiently reduce Cr(VI) to Cr(III) while removing Cr(VI) from water. Therefore, in this study, an efficient green-modified biochar material (TP-nZVI/BC) was successfully prepared using tea polyphenol (TP) and sludge biochar (BC) using a low-cost and environmentally friendly green synthesis method. The preparation conditions of TP-nZVI/BC were optimized using response surface methodology (RSM), revealing that the dosage of tea polyphenols plays a crucial role in the removal performance (R2 = 1271.09), followed by reaction time and temperature. The quadratic regression model proved accurate. The optimal preparation conditions are as follows: tea polyphenols (TP) dosage at 48 g/L, reaction temperature at 75 ℃, and a reaction time of 3 h. TP-nZVI/BC removed Cr(VI) from water at a rate 7.6 times greater than BC. The pseudo-second-order kinetic model (R2 = 0.987) accurately describes the adsorption process, suggesting that chemical adsorption predominantly controls the removal process. The adsorption of Cr(VI) by TP-nZVI/BC can be well described by the Langmuir model, and the maximum adsorption capacity reached 105.65 mg/g. FTIR and XPS analyses before and after adsorption demonstrate that nZVI plays a crucial role in the reduction process of Cr(VI), and the synergistic effects of surface adsorption, reduction, and co-precipitation enhance Cr(VI) removal. In summary, using green-modified biochar for Cr(VI) removal is a feasible and promising method with significant potential.

Flotation performance and adsorption mechanism of α-hydroxyoctyl phosphinic acid to pyrochlore

The flotation performance and adsorption mechanism of α-hydroxyoctyl phosphinic acid (HPA) on pyrochlore were investigated through micro-flotation experiments, zeta-potential tests, contact angle measurements and XPS analysis. The flotation results demonstrated that, in comparison to N-hexadecylpropane-1,3-diamine (NHDA), HPA exhibited a comparable collecting ability for pyrochlore but displayed superior selectivity against feldspar and quartz. Adsorption experiments revealed that the pyrochlore exhibited a higher adsorption capacity for HPA compared to feldspar and quartz. The contact angle experiments indicated that the treatment with HPA significantly increased the contact angle for pyrochlore and calcite, while only minimal changes were observed for feldspar and quartz. Zeta potential and XPS data provided evidence for the chemical adsorption of HPA onto pyrochlore surfaces. Detailed XPS results showed that P-OH groups in HPA formed P(III)-O-M (M = Ca and Nb) bonds with Ca and Nb species on the pyrochlore surface. Additionally, the P-H bond in the HPA molecule could undergo a Redox reaction with highly oxidized Nb, resulting in the formation of a P(V)-Nb(IV) bond. This P(V)-Nb(IV) bond enhances the adsorption of hydrophobic HPA onto the mineral, making it easier to recover pyrochlore through flotation.

Synergistic effects in CuO/SnO2/Ti3C2Tx nanohybrids: Unveiling their potential as supercapacitor cathode material

In the field of materials science, a synergistic effect occurs when the combined physical and chemical properties of a composite material show significant improvement compared to the properties of its individual components. In this study, we synthesized a novel nanosheet-like structure composed of copper oxide (CuO) and tin oxide (SnO2) dispersed on MXene (Ti3C2Tx) sheets using an ultrasonicated coprecipitation method, and then we explored its synergistic effects. The CuO/SnO2/MXene nanohybrids were characterized through SEM, HRTEM, XRD, XPS, and BET analysis, confirming successful synthesis and evident synergy between MXene and CuO/SnO2. The electrochemical behaviour of the nanohybrid structure was investigated using different electrochemical techniques. CuO/SnO2/MXene revealed a high capacitance of 683.5 Fg-1 at 1 Ag-1 in a 2 M H2SO4 electrolyte, with 85 % cycling performance after 10,000 cycles. Notably, this performance surpassed that of MXene-Ti3C2Tx and CuO/SnO2 separately, which achieved only 102.8 and 378.2 Fg-1 capacitance with 60 % and 76 % cycling stability, respectively. These incredible results are attributed to CuO/SnO2/MXene nanohybrids' synergistic effects, whereby enhance the surface area, electrical conductivity, and availability of active sites and enhanced electrochemical performance. This research offers a promising solution for advancing supercapacitor electrode materials through the creation of a novel nanosheet structure that leverages synergistic effects.

Subnanometric Pt-Ga alloy clusters confined within Silicalite-1 zeolite for n-hexane dehydrogenation

Dehydrogenation of light naphtha followed by catalytic cracking into high-value end products can meet the high demand in the world’s petrochemical market. In this work, at attempting synthesis of novel catalysts for hexane dehydrogenation, a series of bimetallic Pt-Ga clusters encapsulated within Silicalite-1 (S-1) catalysts were synthesized using the ligand-protected direct H2 reduction method. The reduced Pt-Ga@S-1-H catalysts comprised restricted ultra-fine Pt-Ga alloys with an average size 0.86–0.95 nm, mainly corresponding to the Pt3 clusters with coordinate number 1.5–2.1. Ga doping significantly improved the catalytic stability, depending on the Ga content, which ranged from 0.02 to 0.27 wt%. As confirmed by the XPS and EXAFS analysis, after the Ga addition, electron transfer occurred between the Pt-Ga alloys and the skeleton oxygen in zeolite, stabilizing the Pt clusters on the zeolite, thereby inhibiting the growth of Pt crystals. During the n-hexane dehydrogenation, the 0.40Pt0.04 Ga@S-1-H catalyst exhibited a hexene selectivity of 87.1 %, achieving a hexene formation rate of 101.4 molhexene∙gPt-1∙h−1 at 550 °C with a WHSV of 90 h−1. After 1000 min of reaction, this best catalyst experienced only slight deactivation with a deactivation constant of 0.066 h−1. The catalytic activity remained almost unchanged after consecutive five cycles of H2 regeneration. DFT calculation using the synchronous structural models showed that the Gibbs free energy changes (−ΔG) for the first three steps of hexane dehydrogenation over the 0.4Pt0.04 Ga@S-1-H catalyst were much lower than those obtained on the 0.4Pt/S-1-H catalyst, suggesting that the introduction of Ga energetically favored the hexane dehydrogenation.

Fabrication of Ni-Polyaniline/Graphene Oxide Composite Electrode with High Capacitance and Water Splitting Activity.

The Ni-PANI@GO composite electrode was fabricated via cost effective electrodeposition technique. According to the XRD, FTIR, Raman, SEM, and XPS analyses revealed that the nickel doped PANI@GO composite has been fabricated on the surface of the nickel foam. Addition of nickel significantly enhanced interaction between graphene with PANI leading to higher degree of polyaniline doping though imine groups. Electrochemical investigation revelated the significant performance of the Ni-PANI@GO composite electrode, boosting an impressive capacitance of 4480 F/g at 40 A/g, surpassing previous Ni-foam-based binder-free electrodes. Notably, Ni-PANI@GO electrode displayed excellent catalytic activity in both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), generating a considerable volume of the gas bubbles at relatively modest overpotentials of 279 mV and 244 mV respectively. This event allows for the achievement of 20 mA·cm-2 current density. Furthermore, in the laboratory-scale water electrolyzer, a low cell voltage of 1.72 V was achieved, facilitating a water-splitting current density of 20 mA·cm-2. This study underscores the premising potential for the real-world device's application of the versatile Ni-PANI@GO composite electrode.