NaBH4 Treatment Research Articles

Flower-like B-FeNiCoP/NF prepared by NaBH4 treatment for water splitting

This paper presents the preparation of a flower-like heterostructure self-supporting working electrode for the purpose of designing an electrolytic water catalyst with high stability and catalytic activity. The study investigates the impact of different ratios of nickel, cobalt, and iron on the microstructure and catalytic performance of the electrode. It was found that a Fe:Ni:Co ratio of 1:1:1 resulted in fluffy nanowires dispersed on nanosheets of flower-like nanoflowers, leading to an increase in specific surface area. Additionally, the heterogeneous structure of NiCoP and Fe2P significantly enhanced the catalytic performance of the electrode. The exceptional electrocatalytic performance of B-FeNiCoP/NF can be attributed to the synergistic interface effect and the presence of numerous exposed active sites. In the electrochemical evaluation of the hydrogen evolution reaction (HER), an overpotential of 185.5 mV at a current density of 100 mA cm−2 has been identified as sufficient, with a difference of 35.9 mV compared to Pt-C and a Tafel slope of 58.3 mV/dec. In the assessment of the oxygen evolution reaction (OER), an overpotential of 301.8 mV at a current density of 100 mA cm−2 was found necessary, with a discrepancy of 18.2 mV compared to RuO2 and a Tafel slope of 69.5 mV/dec. The stability assessment of the HER and OER at a current density of 100 mA cm−2 over a duration of 48 hours demonstrated exceptional stability. This study introduces a hydrothermal pretreatment method for sodium borohydride, which has the potential to enhance the phosphorylation of catalytic application systems.

Optimization of Wet-Spun PEDOT:PSS Fibers for Thermoelectric Applications Through Innovative Triple Post-treatments

Owing to the high flexibility, low thermal conductivity, and tunable electrical transport property, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) exhibits promising potential for designing flexible thermoelectric devices in the form of films or fibers. However, the low Seebeck coefficient and power factor of PEDOT:PSS have restricted its practical applications. Here, we sequentially employ triple post-treatments with concentrated sulfuric acid (H2SO4), sodium borohydride (NaBH4), and 1-ethyl-3-methylimidazolium dichloroacetate (EMIM:DCA) to enhance the thermoelectric performance of flexible PEDOT:PSS fibers with a high power factor of (55.4 ± 1.8) μW m−1 K−2 at 25 °C. Comprehensive characterizations confirm that excess insulating PSS can be selectively removed after H2SO4 and EMIM:DCA treatments, which induces conformational changes to increase charge carrier mobility, leading to enhanced electrical conductivity. Simultaneously, NaBH4 treatment is employed to adjust the oxidation level, further optimizing the Seebeck coefficient. Additionally, the assembled flexible fiber thermoelectric devices show an output power density of (60.18 ± 2.79) nW cm−2 at a temperature difference of 10 K, proving the superior performance and usability of the optimized fibers. This work provides insights into developing high-performance organic thermoelectric materials by modulating polymer chains.Graphical

Sustainable approach for CO2 hydrogenation to formic acid with Ru single atom catalysts on nitrogen-doped carbon prepared from green algae

Ruthenium catalysts supported on nitrogen-doped carbon (NDC) have gained attention due to their exceptional catalytic performance for CO2 hydrogenation to formic acid, a key solution to mitigate CO2 emissions. However, conventional methods for preparing NDC typically rely on petrochemical compounds, which are not environmentally friendly. Herein, we propose a sustainable and innovative approach by employing protein-rich green algae as a source to prepare NDC for Ru catalysts. To maximize the CO2 reduction effect, flue gas exhausted from industrial processes was utilized as a CO2 feed to cultivate the green algae in a photobioreactor. The harvested green algae were pyrolyzed at 800 °C under an N2 atmosphere to prepare the NDC. After the metalation of Ru on prepared NDC, the Ru catalysts exhibited a turnover number of 7,599 for CO2 hydrogenation which demonstrated the potential of green algae as a raw material for NDC. However, the catalysts were deactivated due to the leaching or agglomeration of weakly bound Ru analyzed by experimental and theoretical investigations. We applied a NaBH4 treatment to stabilize the Ru active sites, and the treated catalysts retained 99.6 % of their initial catalytic activity after five recycling tests. Furthermore, Ru on NDC achieved a cumulative turnover number of 16,000 after 24 h. This study offers a sustainable and eco-friendly method for reducing CO2 emissions, combining the cultivation of green algae with waste flue gas and the production of formic acid via CO2 hydrogenation using improved Ru catalysts on algae-derived NDC.

Regulation of surface structure to suppress voltage decay for high-stable Li-rich oxide cathodes

Layered lithium-rich manganese oxides (LMO) are promising cathode materials for high-energy density lithium-ion batteries due to their high specific capacity and working potential. However, serious voltage decay and undesirable cycle stability are big obstacles that hinder their industrialization and application. Herein, an innovative and industrially valuable strategy of constructing composite coatings and oxygen vacancies on the LMO surface is put forward to suppress voltage decay and enhance the cycling stability of LMO by precisely modulating NaBH4 treatment. The synergistic effect of surface spinel coating, NaBO2coating, and oxygen vacancies effectively inhibits the release of oxygen, impedes the occurrence of side reactions at the interface, inhibits the migration and dissolution of transition metals, suppresses the irreversible structure transformation and improves the reversibility of redox reaction. The capacity retention of the NaBH4-treated LMO material maintains 100 % after 200 cycles at 0.5C, as well as stable cycling at 2C with a discharge capacity of 180 mAh g−1 harvested. Moreover, the voltage decay is significantly suppressed by NaBH4 modification, especially the NaBH4-0.5 % sample exhibits a mere voltage decay of 1.73 mV per cycle in the 200 cycles. This study provides significant insights into the development of LMO cathodes with long-cycle performance.

Boosting thermoelectric performance of single-walled carbon nanotubes-based films through rational triple treatments

Single-walled carbon nanotubes (SWCNTs)-based thermoelectric materials, valued for their flexibility, lightweight, and cost-effectiveness, show promise for wearable thermoelectric devices. However, their thermoelectric performance requires significant enhancement for practical applications. To achieve this goal, in this work, we introduce rational “triple treatments” to improve the overall performance of flexible SWCNT-based films, achieving a high power factor of 20.29 µW cm−1 K−2 at room temperature. Ultrasonic dispersion enhances the conductivity, NaBH4 treatment reduces defects and enhances the Seebeck coefficient, and cold pressing significantly densifies the SWCNT films while preserving the high Seebeck coefficient. Also, bending tests confirm structural stability and exceptional flexibility, and a six-legged flexible device demonstrates a maximum power density of 2996 μW cm−2 at a 40 K temperature difference, showing great application potential. This advancement positions SWCNT films as promising flexible thermoelectric materials, providing insights into high-performance carbon-based thermoelectrics.

Constructing partially amorphous NiMoB/NiMoO4-x with borate doping and reduction through one step boosting hydrogen evolution

The pursuit of efficient and stable electrochemical catalysts based on transition metals (TMs) for the hydrogen evolution reaction (HER) is of paramount importance. Herein, a novel partially amorphous NiMoB/NiMoO4-x catalyst with dense nanoparticle assemblies has been prepared with B doping and reduction by one step NaBH4 treatment of smooth nanorod-like NiMoO4 precursor. Benefiting from the MoNi4 alloys partially reduced from NiMoO4 precursor, optimized electronic state through B doping and partially amorphous structure, NiMoB/NiMoO4-x obtained splendid activity for HER with a lower overpotential of 26.2mV at 10mAcm2 coupled with a narrow Tafel slope of 66.75mV dec1, in contrast to NiMoO4 precursor catalyst (260.24@10mAcm2, 149mV dec1) in alkaline solution. Additionally, the self-supported NiMoB/NiMoO4-x electrode exhibits remarkable stability, maintaining a current density of 50mAcm2 for a minimum of 40hours attributed to mixed phases of MoNi4 and amorphous NiMoO4-x for accelerating the H2 evolution and enhancing water adsorption. This work offers a facile avenue to rationally design high-performance electrocatalysts for enhancing hydrogen evolution with NaBH4 accompanying borate doping and reduction.

Facilitated catalytic surface engineering of MnCo2O4 electrocatalyst towards enhanced oxygen evolution reaction

The overall conversion efficiency of water electrolysis is primarily restricted by the sluggish kinetics of the oxygen evolution reaction (OER). To overcome the OER bottleneck, fundamental scientific attention is keenly directed toward the development of durable, cost-effective, and highly efficient catalysts, and therefore, the focus of current research. Herein, we report the facile fabrication of promising noble–metal–free oxygen defects engineered MnCo2O4 (Od-MnCo2O4) catalyst as a highly efficient OER water electrocatalyst in an alkaline KOH medium. The MnCo2O4 nanosheet is directly grown on the nickel foam and dramatically changes to a crumpled sphere after NaBH4 treatment, which results in increased oxygen defects (Od). The engineered Od in MnCo2O4 might modify their electronic structure effectively, which results in improved electrical conductivity and a large quantity of electrochemically accessible active surface area. The Od-MnCo2O4 catalyst demonstrates an outstanding OER activity and exhibits a small overpotential of 250 and 316 mV at a current density of 10 and 100 mA cm−2, respectively, with a modest Tafel slope of 64 mV dec–1. The Od-MnCo2O4 catalyst also demonstrates excellent perseverance till 60 h upon continuous chronopotentiometric test even at 100 mA cm−2 and further reveals a static potential response at low and high rates. The excellent OER performance is ascribed to enhanced electrochemically active sites and improved electronic conductivity aroused from the NaBH4 reduction.

Copper Nanoparticles Supported on ZIF-8: Comparison of Cu(II) Reduction Processes and Application as Benzyl Alcohol Oxidation Catalysts.

We report the synthesis of a stable heterogeneous catalyst based on copper metal nanoparticles with oxidized surface supported on ZIF-8 for the oxidation of benzyl alcohol under mild temperature and using air as a sustainable oxygen source as well as for the implementation of the tandem "one-pot" catalytic system allowing the sustainable synthesis of benzylidene malononitrile. The influence of the reduction process applied to form the nanoparticle upon the catalyst texture and its performances was extensively examined. After ZIF-8 impregnation with a copper chloride precursor, the reduction of cupric ions into Cu0 nanoparticles was carried out according to two procedures: (i) by soaking the solid into a solution of NaBH4 and (ii) by submitting it to a flow of gaseous H2 at 340 °C. The in-depth physicochemical characterization and comparison of the resulting two types of Cu/ZIF-8 materials reveal significant differences: the reduction with NaBH4 led to the formation of 16 nm sized Cu0 nanoparticles (NP) mainly localized on the external surface of the ZIF-8 crystals together with ZnO nanocrystallites, while the reduction under H2 flow resulted in Cu0 nanoparticles with a mean size of 22 nm embedded within the bulk of ZIF-8 crystals. More, when NaBH4 was used to reduce cupric ions, ZnO particles were highlighted by high-resolution microcospy imaging. Formation of ZnO impurities was confirmed by the photoluminescence analysis of ZIF-8 after NaBH4 treatment. In contrast, ZnO was not detected on ZIF-8 treated with H2. Both types of Cu0 NPs supported on ZIF-8 were found to be active as catalysts toward the aerobic oxidation of benzyl alcohol under moderate temperature (T < 80 °C) and using air as a sustainable O2 source. Benzaldehyde yield of 66% and selectivity superior to 90% were obtained with the Cu/ZIF-8 catalyst prepared under H2 flow after 24 h under these conditions. The same material could be recycled 5 times without loss of activity, unlike the catalysts synthesized with NaBH4, as a result of the leaching of the surface copper NPs over the consecutive catalytic cycles. Finally, the most stable catalyst was successfully implemented in a tandem "one-pot" catalytic system associating benzyl alcohol oxidation and Knoevenagel condensation to synthesize benzylidene malononitrile.

Mechanism of high PEC performance of B-doped TiO2 nanotube arrays: Highly reactive surface defects and lattice stress

The role of the boron (B) doping induced defect state in the PEC process is still unclear though B doped TiO2 nanotube arrays (TNAs) via anodic oxidation has commonly used to improve the photocatalytic decomposition of water by TNAs. Therefore, this work aims to establish the underlying reasons for the high PEC reactivity and stability maintained by the B doping induced defective states. Special attention is paid to the differences in carrier behavior and surface reactivity in the PEC process between the B doped induced and NaBH4 treatment induced defective states. DFT calculations show that B doping can effectively reduce the generation energy of Ti3+/Vo (oxygen vacancies) pairs and enhance the adsorption energy of defects on the surface of TiO2 (101) for H2O and ·OH. Moreover, due to the presence of B atoms, the surface defects of TiO2 can maintain high adsorption of H2O and ·OH, without being deactivated by the healing of oxygen vacancies, which ensures the stability and activity of the catalyst. Meanwhile, the lattice stress induced by B doping forms the internal electric field, which ensures the efficient separation of carriers in the bulk phase and avoids the negative effect of bulk phase defects on carrier separation.

Charge transfer interactions exist in extracellular polymeric substances: Comparison with natural organic matter

Extracellular polymeric substances (EPS) and natural organic matter (NOM) are widely present in the environment. While the molecular basis of NOM's optical properties and reactivity after treatment with sodium borohydride (NaBH4) has been successfully explained by the charge transfer (CT) model, the corresponding structure basis and properties of EPS remain poorly understood. In this work, we investigated the reactivity and optical properties of EPS after NaBH4 treatment, comparing them to the corresponding changes in NOM. After reduction, EPS exhibited optical properties and a reactivity with Au3+ similar to NOM, manifesting an irreversible loss of visible absorption (≥70%) associated with blue-shifted fluorescence emission (8–11 nm) and a lower rate of gold nanoparticles formation (decreasing by ≥ 32%), which can be readily explained by the CT model as well. Furthermore, the absorbance and fluorescence spectra of EPS were solvent polarity dependent, contrary to the superposition model. These findings contribute to an original understanding of the reactivity and optical properties of EPS and facilitate further cross-disciplinary studies.

MOF-derived spherical NixSy/carbon with B-doping enabling high supercapacitive performance

This work uses a simple Ni-metal organic framework (Ni-MOF) to generate a uniform metal-containing carbon hybrid structure of Ni/C by in-situ pyrolysis. Then, after NaBH4 treatment and hydrothermal vulcanization of Ni/C, multiphase B-doped NixSy nanoparticles can be obtained and uniformly anchored in the carbon skeleton, forming a highly porous flower-shaped B-NixSy/C composite. The positive role of B doping was theoretically confirmed by Density Function Theory (DFT) calculations. The MOF-derived carbon framework has porous, conductive, and continuous features beneficial for fast charge transfer. There are also multiple Ni-sulfide phases in B-NixSy/C, dominated by hexagonal NiS, hexagonal Ni2S3, and cubic Ni3S4, which give rich valance state and are expected to bring active electrochemical reactions. In addition, the boronation process by the reducing agent of NaBH4 is also proved beneficial to bring high capacitance, possibly due to the incorporation of more active sites by B. Therefore, the B-NixSy/C composite electrode delivers a high specific capacity of 1250.4 C g–1 at 1 A g–1 and excellent rate performance. The B-NixSy/C-based asymmetric supercapacitor also shows promising prospects for future energy storage devices, delivering high cyclability with capacitance retention of 87.6% after 7000 cycles. This work proves the efficiency of MOF-derived carbon framework and B-doping in improving metal sulfide's electrochemical performances.

Strengthening chlorobenzene catalytic degradation rate over LaxSr1-xMnO3±δ by anchoring interfacial oxygen vacancy

Surficial lattice oxygen in perovskite compounds is a common participant during chloroaromatic catalytic degradation. Herein, we proposed a facile oxygen vacancy construction strategy for preparing high active LaxSr1-xMnO3±δ (LSMO) via NaBH4 treatment. Results reveal that LSMO composites are not only reduced by NaBH4 under mild condition, but also triggering a significant Sr segregation effect, which plays a key role in oxygen vacancy formation accounting to the electron donation from Sr to Mn acceptor and subsequent lattice oxygen activation. Moreover, the concentration of interfacial active oxygen species can be regulated by taming the La-Sr interaction with different Sr substitution proportions. The anchored oxygen vacancies (OVs) take advantage of electron capture or transfer and induce molecule oxygen into active oxygen species to react with chlorobenzene molecules, resulting in a preferential catalytic oxidation capacity. Amongst, reduced La0.5Sr0.5MnO3±δ catalyst displays superior chlorobenzene destruction efficiency with 90% of which converted as low as 236 °C, which also exhibits a stable performance in long-time operation. However, the OVs would be refilled by H2O molecules and results in a weaker water resistance for OVs anchored catalyst. In summary, the annihilation of OVs is the most important factor for catalyst deactivation. The research offers a new avenue to construct interfacial oxygen species in perovskite oxides during the chlorobenzene deep oxidation process.

Oxygen vacancies-rich α@δ-MnO2 mediated activation of peroxymonosulfate for the degradation of CIP: The role of electron transfer process on the surface

The environmental-friendly manganese oxides play an important role in the degradation of organic pollutants through radical or non-radical pathway. In this work, the oxygen vacancies (OVs)-rich α@δ-MnO2 (OVs-α@δ-MnO2) was synthesized via a one-step hydrothermal method and used to activate peroxymonosulfate (PMS) for the degradation of antibiotic ciprofloxacin (CIP). OVs-α@δ-MnO2 displayed remarkable catalytic activity with almost 100 % elimination of 20 mg/L CIP within 15 min, which presented better catalytic performance than δ-MnO2 or α-MnO2. OVs-α@δ-MnO2 acts as a shuttle for electron transport from CIP to PMS. The CIP degradation was almost inhibited completely by the addition of 1 mM HPO42-, indicating that the reaction only occurred on the surface of catalyst. The quenching experiments, analysis of electron paramagnetic resonance (EPR), N2 pumping experiments and the comparison of the furfuryl alcohol (FFA) degradation suggested that the contributions of OH, SO4−, O2− and 1O2 could be negligible. The introduction of OVs increases the Mn3+ content in catalyst, improves the ability of combination with PMS and accelerates the reduction of part of Mn4+ in the reactions. OVs-α@δ-MnO2 exhibits excellent catalytic capability in various water conditions including different pH and coexisting anions based on the non-radical electron transfer mechanism. The CIP degradation gradually decreased over the fourth cycles due to the increase of Mn valence states and the coverage of OVs on the surface, but it could be regenerated by a simple NaBH4 treatment in alkaline condition. The intermediate products and possible degradation pathway were identified by UPLC-MS/MS and proposed based on the degradation mechanisms. This study provides a simple method to synthesize OVs-based MnO2 material and presents deep insights into the electron transfer mechanisms in PMS activation processes.

Experimental and theoretical elucidation of adsorption performance and mechanism of surface-engineered BiVO4 hollow cuboids for removing MB and other pollutants

To expand the application of BiVO4 (BVO) in removing environmental pollutants as an adsorbent, it is imperative to develop an efficient way to engineer its adsorption performance and understand the underlying mechanism. To achieve this aim, herein we have firstly synthesized a new type of BVO hollow cuboids (length 1.8–4 μm, width 1–1.5 μm) via a hydrothermal reaction route, and then created O vacancies on their surface via NaBH4 treatment. The adsorption experiment for removal of methylene blue (MB) demonstrates that the surface-engineered BVO using 0.4 M NaBH4 solution exhibits an adsorption performance about 96.4 times greater than that of pristine BVO; and the value of qe is predicted by response surface methodology (RSM) to be 74.115 mg g−1 at the operation parameters CBVO = 0.1 g L−1, CMB = 40 mg L−1 and T = 10 °C. The adsorption kinetics, isotherms and thermodynamics analyses manifest that the dye adsorption process is a spontaneous, exothermic and heterogeneous multilayer adsorption process. Density functional theory (DFT) calculations suggest the creation of O vacancy significantly increases the adsorption energy of MB on the BVO surface, from −0.0375 eV for perfect BVO to −0.1204 eV for O1-vac-BVO. The adsorption mechanism of the surface-engineered BVO was elucidated based on the experimental data and theoretical calculations. Furthermore, their adsorption behaviors in removing various cationic and anionic organic dyes in different acidic-alkaline environments were evaluated.

Polypyrrole-Coated Low-Crystallinity Iron Oxide Grown on Carbon Cloth Enabling Enhanced Electrochemical Supercapacitor Performance

It is highly attractive to design pseudocapacitive metal oxides as anodes for supercapacitors (SCs). However, as they have poor conductivity and lack active sites, they generally exhibit an unsatisfied capacitance under high current density. Herein, polypyrrole-coated low-crystallinity Fe2O3 supported on carbon cloth (D-Fe2O3@PPy/CC) was prepared by chemical reduction and electrodeposition methods. The low-crystallinity Fe2O3 nanorod achieved using a NaBH4 treatment offered more active sites and enhanced the Faradaic reaction in surface or near-surface regions. The construction of a PPy layer gave more charge storage at the Fe2O3/PPy interface, favoring the limitation of the volume effect derived from Na+ transfer in the bulk phase. Consequently, D-Fe2O3@PPy/CC displayed enhanced capacitance and stability. In 1 M Na2SO4, it showed a specific capacitance of 615 mF cm-2 (640 F g-1) at 1 mA cm-2 and still retained 79.3% of its initial capacitance at 10 mA cm-2 after 5000 cycles. The design of low-crystallinity metal oxides and polymer nanocomposites is expected to be widely applicable for the development of state-of-the-art electrodes, thus opening new avenues for energy storage.

Enhanced cycling performance of surface-amorphized Co3S4 as robust cathode for supercapacitors

The interfacial engineering via surface amorphization is an effective strategy to regulate the structure and character of material. Herein, a facile hydrothermal method followed by NaBH4 treatment is proposed to fabricate surface-amorphized Co3S4 (SA-Co3S4). XRD and SEM characterization implies the micro flower structure of Co3S4. TEM test further demonstrates the heterointerface between crystal Co3S4 core and defect-rich amorphous Co3S4 surface, which can reduce electron/ion transport path and accelerate internal charge transfer rate, thus enhancing the integral electrical conductivity. Electrochemical measurements imply that the SA-Co3S4 displays satisfying specific capacitance of 1043.9 F g−1 at 0.5 A g−1 and good rate performance. By employing SA-Co3S4 as a cathode, and active carbon as an anode, the asymmetric supercapacitor exhibits a high energy density of 41.9 Wh kg−1 at a power density of 162 W kg−1 and good cycling durability (above 90 % retention rate after 10,000 cycles). This work offers a novel structure design strategy for fabricating cobalt sulfide materials with high conductivity and electrochemical performances.

Photoelectrochemical study of Ti3+ self-doped Titania nanotubes arrays: A comparative study between chemical and electrochemical reduction

Water splitting through the photoelectrochemical process is a solid strategy to produce clean hydrogen for which TiO2 isconsideredthe most potential photoanode due to its unique properties. However, its wideband gap and high charge carrier recombination rate limit its solar-to-hydrogen conversion efficiency. Here in we report the fabrication of the Ti3+ self-doped TiO2 nanotube samples prepared through electrochemical and Chemical (NaBH4 treatment) reduction. Structural and morphological analysis carried through XRD and FESEM respectively confirmed the formation of TiO2 nanotube arrays. XPS spectra were used to affirm the presence of Ti3+ states in the reduced sample. The absorption edge observed in the 430–500 nm range validated the reduction of the band gap to the visible range in Ti3+ self-doped samples. Photoelectrochemical results of both the reduced samples evince their potential applicability as a photoanode for hydrogen generation through PEC water splitting. EIS and absorbance spectra reveal that larger charge density, faster electron-hole separation, and better visible light absorption may be thefactors that contribute to reducing TiO2′s superior photoelectrochemical performance. However, a comparative study shows better results for electrochemically reduced samples, suggesting it is an effective technique than chemical reduction.

Introducing oxygen vacancies on sodium titanate via NaBH4 treatment for conductometric hydrogen gas sensors

Sodium titanate (NTO) has drawn great attentions in various applications, but few works focus on using NTO as gas sensors. The implication of NTO as gas sensors requires a simple synthesis route to fabricate NTO with large surface areas and oxygen vacancies. Herein, Pd-decorated NTO microscale hierarchical spheres (Pd-NTO MHSs) is synthesized using Ti foil as a precursor·H2O2 is added to promote the preparation of NTO MHSs under a low base-concentration and low temperature condition, making the synthetic route more eco-friendly than previously methods. Additionally, we demonstrate NaBH4 reduction is a one-step process that simultaneously decorates Pd nanoparticles and brings abundant oxygen vacancies on the NTO surface, but too high NaBH4 concentration deteriorates the hydrogen sensing performance. At the optimized condition, Pd-NTO MHSs have a response time of ∼1.8 s to 1% H2 and a wide detection range of 10 ppm to 10% H2 at 25 °C. This study highlights that NaBH4 treatment is an effective strategy for regulating surface chemical properties and introducing oxygen vacancy on NTO, enabling Pd-NTO MHSs an excellent sensing property. It is also helpful for the rational design of NTO as a versatile sensing material with abundant oxygen vacancies to sense other gases.

Mo‐Doped Sulfur‐Vacancy‐Rich V1.11S2 Nanosheets for Efficient Hydrogen Evolution

AbstractHigh‐performance low‐cost hydrogen evolution electrocatalysts are urgently demanded for hydrogen production by water splitting. Herein, we report that an efficient defect engineering strategy, NaBH4 treatment, was employed to promote the HER activity of pre‐synthesized Mo‐doped V1.11S2 nanosheets. The abundant sulfur vacancies enable Mo‐doped V1.11S2 petaloid nanosheets with a low overpotential of 160 mV and a small Tafel slope of 46.2 mV dec−1 at 10 mA cm−2 to drive the HER, as well as excellent long‐term stability in 0.5 mol L−1 H2SO4. The outstanding electrocatalytic performance can be attributed to the large electrochemical surface area and low charge transfer resistance.

Heteroatom Modification of Heterostructured CuS/Mn3O4 with Rich Defects for Solid-State Supercapacitors

Heterostructure construction and heteroatom modification are considered as effective approaches to modulate the electronic structure and boost the energy storage activity of electrode materials. Herein, oxygen-modified CuS/Mn3O4 (O-CuS/Mn3O4) heterogeneous nanoflakes with abundant defects are fabricated by solid-state grinding followed by NaBH4 treatment (NBHT) at room temperature using MnCu Prussian blue analogue (MnCu-PBA) as the precursor. During the NBHT, a portion of the sulfur atoms in CuS is removed, and the remaining sites in the lattice are occupied by oxygen in the water, resulting in an oxygen modification. Experimental results and theoretical calculations confirm that heterojunction, defect, and oxygen modification not only greatly facilitate the adsorption of OH– on the surface of the electrode material but also endow improved electrical conductivity, wettability, specific surface area, and active sites. Benefiting from these advantages, O-CuS/Mn3O4 exhibits an excellent specific capacitance of 1307 F g–1 at 1 A g–1. Moreover, the solid-state asymmetric supercapacitor with O-CuS/Mn3O4 and MnO2 (O-CuS/Mn3O4//MnO2) shows an outstanding energy density of 34.4 Wh kg–1 at 800.1 W·kg–1 and cyclic stability with 85.7% capacitance retention after 5000 cycles at 6 A g–1. Our work highlights the integration of heterojunction and oxygen modification to fabricate and optimize the energy storage electrode materials.