HO Bond Research Articles

Cu-Co binary metal-organic framework nanosheets for highly efficient degradation of norfloxacin using the Fenton-like process

Efficient catalyst development for hydrogen peroxide activation is crucial in advanced oxidation processes (AOPs) technology. In this study, we successfully synthesized a bimetallic organic framework incorporating Cu-Co MOF nanosheets via a one-pot strategy. The subsequent Cu-Co MOF nanosheets demonstrated outstanding oxidative activity, achieving a remarkable 95.37 % removal of norfloxacin (NOR), surpassing the efficacy of Cu MOF/H2O2 or Co MOF/H2O2 nanosheets alone by 1.34 and 2.59 times, respectively. Density functional theory (DFT) calculations revealed that the bimetallic MOF nanosheets: firstly, enhanced optimization of the adsorption energy for H2O2 activation; and secondly, facilitated the cleavage of the O–O bond in H2O2. Furthermore, electrochemical impedance spectroscopy (EIS) analysis demonstrated a significant improvement in interfacial electron transfer once dual-reaction centers were introduced into the Cu-Co MOF nanosheets. Electron paramagnetic resonance analysis and quenching tests confirmed that 1O2, ·O2− and ·OH were involved in NOR degradation. Reasonable NOR degradation pathways were proposed by analysing the results of LC-MS and DFT calculations. Moreover, the synthesized nanosheets exhibited excellent reusability, with more than 90.00 % NOR removal achieved using the Cu-Co MOF nanosheets/H2O2 system after reuse on 3 occasions. These findings underscore the effectiveness of bimetallic MOF construction in developing highly efficient MOF-based Fenton-like catalysts. Also highlighted here is the promising role of Cu-Co MOF nanosheets in wastewater treatment, particularly for the removal of antibiotics.

Effect of temperature on the symmetrization of AlOOH hydrogen bonds

Hydrogen bonding symmetrization of water-bearing minerals plays a key role in the water cycle of the deep Earth. The lower mantle is a high-temperature and high-pressure environment, and in this study a classical molecular dynamics simulation of the δ-AlOOH hydrogen bond symmetrization process is carried out using a deep learning potential model. Calculation the length of the HO bond reveals that AlOOH undergoes hydrogen bond symmetrization when the pressure reaches 9 GPa. The volume thermal expansion profile of AlOOH shows an anomalous phenomenon of negative correlation between phase transition pressure and temperature. The radial distribution functions gOH(r) and gHH(r) show the asymmetry of hydrogen bonding at 8 GPa and indicate the critical conditions for hydrogen bonding symmetry at 10 GPa. Calculations of the O1O2 bond lengths show that the critical pressure required for hydrogen bond symmetry increases with temperature. Our simulation results provide some insight into the hydrogen bonding symmetry of water-bearing minerals in the deep Earth’s.

"Marriage" of Inorganic to Organic Chemistry as Motivation for a Theoretical Study of Chloroform Hydrolysis Mechanisms.

Incorporation of chlorides in coordination complexes, prepared by reactions in CHCl3, stimulated MP2 and DFT studies of its complete hydrolysis mechanisms. In excellent agreement with previous experimental results, the most important mechanism for CHCl3 basic hydrolysis at room temperature is the radical one producing :CCl2. The latter inserts into the H-O bond of H2O yielding dichloromethanol (1). The hydrolysis mechanism of α-H-lacking PhCCl3 to the corresponding dichloro(phenyl)methanol (3) was also studied. 1 decomposes by H2O to formyl chloride (2) and HCl. 2, following a variety of pathways, leads to known CHCl3 hydrolysis products, such as CO (4) and formic acid (6), via the intermediates chloromethanediol (5), s-cis, s-trans-dihydroxycarbene (ct-7), and s-trans, s-trans-dihydroxycarbene (tt-7). Interestingly, both ct-7 and tt-7 intermediates have recently been implicated in the reduction of CO2 with H2 to 6. The conversion of CO to HCOOH was studied. Most of the reactions studied are asynchronous concerted processes, the radical mechanism being a multistep one. The synthetic utility of this mechanism is briefly mentioned. To avoid chloride ions when performing reactions in CHCl3, we should use the solvent at room temperature even in the presence of water. This has been verified further by coordination chemistry reactions in progress.

Plasmonic Pt-PPCN/TiN Ohmic Junction for Photo-Thermo Catalytic Hydrogen Production.

The rational design of photocatalysts for improving the conversion of solar energy into hydrogen is a promising route for achieving carbon neutrality. Herein, we couple plasmonic titanium nitride (TiN) with highly crystalline potassium-doped polymeric carbon nitride (PPCN) to construct a PPCN/TiN ohmic junction. Such an ohmic junction not only broadens the absorption spectrum but also inhibits the recombination of electrons and holes. In addition, Pt nanoparticles are introduced into this ohmic junction to form plasmonic Pt-PPCN/TiN, improving the capture of hot electrons generated by TiN and thereby promoting the dissociation of the O-H bond in H2O. The energy barrier decreases from 0.7 to 0.2 eV. Enhanced separation of carrier, activation of water molecules, and capture of hot electrons are jointly promoting photo-thermo catalytic hydrogen production. Therefore, under full-spectrum irradiation, the hydrogen production rate of Pt-PPCN/TiN reaches 19 085 μmol g-1 h-1. This novel plasmonic photocatalyst is promising for full-spectrum photo-thermo catalytic hydrogen production.

P–d Orbitals Coupling Heterosites of Ni2P/NiFe‐LDH Interface Enable O─H Cleavage for Water Splitting

AbstractElectrocatalytic water splitting for hydrogen production still faces a bottleneck due to sluggish reactive kinetics and high reactive energy barriers. Herein, p–d orbital coupling P–Fe heterosites are constructed at Ni2P–FeNi‐LDH interfaces to enhance the O─H bond cleavage of reaction intermediates H2O* and OH* for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. The Ni2P/NiFe‐LDH heterostructure shows superior HER and OER activities for alkaline water splitting with overpotentials of 230 and 270 mV at 100 mA cm−2, respectively, and even exhibits high activity for electrocatalytic alkaline seawater splitting. The interaction of P 2p and Fe 3d orbitals at Ni2P–FeNi‐LDH interfaces upshifts the d‐band center of Fe and downshifts the p‐band center of P. This finding not only facilitates the dissociation of O─H bonds in H2O and promotes the Volmer–Heyrovsky step for HER, but also reduces the energy barrier for the rate‐determining step of OER from OH* to O* transition. This work proposes a new approach to constructing p–d heterosites at heterojunctions to facilitate reactive kinetics and reduce the energy barrier for electrocatalysis.

Pre-Adsorbed H-Mediated Electrochemiluminescence.

In conventional electrochemiluminescence (ECL) systems, the presence of the competitive cathodic hydrogen evolution reaction (HER) in aqueous electrolytes is typically considered to be a side reaction, leading to a reduced ECL efficiency and stability due to H2 generation and aggregation at the electrode surface. However, the significant role of adsorbed hydrogen (H*) as a key intermediate, formed during the Volmer reaction in the HER process, has been largely overlooked. In this study, employing the luminol-H2O2 system as a model, we for the first time demonstrate a novel H*-mediated coreactant activation mechanism, which remarkably enhances the ECL intensity. H* facilitates cleavage of the O-O bond in H2O2, selectively generating highly reactive hydroxyl radicals for efficient ECL reactions. Experimental investigations and theoretical calculations demonstrate that this H*-mediated mechanism achieves superior coreactant activation compared to the conventional direct electron transfer pathway, which unveils a new pathway for coreactant activation in the ECL systems.

Cu2(OH)3NO3/γ-Al2O3 catalyzes Fenton-like oxidation for the advanced treatment of effluent organic matter (EfOM) in fermentation pharmaceutical wastewater: The synergy of Cu2(OH)3NO3 and γ-Al2O3

The secondary effluent of fermentation pharmaceutical wastewater exhibits high chromaticity, elevated salinity, and abundant refractory effluent organic matter (EfOM), presenting significant treatment challenges and environmental threats. Herein, Cu2(OH)3NO3/γ-Al2O3 was fabricated through ultrasound-assisted impregnation and calcination to catalyze the Fenton-like oxidation for degrading organic pollutants in this secondary effluent. Under neutral conditions, with 400.00 mg/L H2O2, 8 g/L catalyst, and at 30 ℃, the EfOM and CODCr removal efficiencies can reach 96.90 % and 51.56 %, respectively. The Cu2(OH)3NO3/γ-Al2O3 catalyst possesses ideal reusability, maintaining CODCr, chromaticity, and EfOM removal efficiencies at 44.44 %-64.59 %, 85.45 %-93.45 %, and 61.00 %-95.00 % over 220 h in a continuous-flow catalytic oxidation system operated at room temperatures (15–25 ℃). Electron paramagnetic resonance results and density functional theory calculations indicate that •OOH may be the predominant reactive oxygen species, facilitated by the easier elongation of the OH bond in H2O2 compared to the OO bond. The adjusted electronic structure endows Cu2(OH)3NO3/γ-Al2O3 composite sites with superior catalytic selectivity for H2O2 activation compared to Cu2(OH)3NO3 single crystal sites, with γ-Al2O3 additionally facilitating H2O2 activation through electron donation. This research highlights the efficacy of Cu2(OH)3NO3/γ-Al2O3 in the advanced treatment of complex industrial wastewater, elucidating its catalytic mechanisms and potential applications.

Protons intercalation induced hydrogen bond network in δ-MnO2 cathode for high-performance aqueous zinc-ion batteries

Birnessite-type MnO2 (δ-MnO2) exhibits great potential as a cathode material for aqueous zinc-ion batteries (AZIBs). However, the structural instability and sluggish reaction kinetics restrict its further application. Herein, a unique protons intercalation strategy was utilized to simultaneously modify the interlayer environment and transition metal layers of δ-MnO2. The intercalated protons directly form strong O H bonds with the adjacent oxygens, while the increased H2O molecules also establish a hydrogen bond network (O H···O) between H2O molecules or bond with adjacent oxygens. Based on the Grotthuss mechanism, these bondings ultimately enhance the stability of layered structures and facilitate the rapid diffusion of protons. Moreover, the introduction of protons induces numerous oxygen vacancies, reduces steric hindrance, and accelerates ion transport kinetics. Consequently, the protons intercalated δ-MnO2 (H-MnO2-x) demonstrates exceptional specific capacity of 401.7 mAh/g at 0.1 A/g and a fast-charging performance over 1000 cycles. Density functional theory analysis confirms the improved electronic conductivity and reduced diffusion energy barrier. Most importantly, electrochemical quartz crystal microbalance tests combining with ex-situ characterizations verify the inhibitory effect of the interlayer proton environment on basic zinc sulfate formation. Protons intercalation behavior provides a promising avenue for the development of MnO2 as well as other cathodes in AZIBs.

The electronic and optical properties of Al interstitial defects in KH2PO4 crystal: First principles study

KH2PO4 (KDP) crystals are widely used as frequency multipliers in inertial confinement controlled fusion ignition devices. The electronic and optical properties of KDP crystals with Al interstitial defects based on first principles are investigated. The results show that neutral and +3 charged Al interstitial can exist stably in the crystal. The +3 charged defect produces a larger lattice distortion. Bond length varies from −18.78 % to 43.71 % in the paraelectric phase(P-KDP) and from −25.57 % to 66.09 % in the ferroelectric phase (F-KDP). At the same time, +3 charged Al interstitial may also cause HO bond to break, resulting in the generation of H interstitials, which may compensate for the H vacancies in as-grown KDP. This may make the laser damage threshold slightly increase when KDP crystal is doped with +3 charged Al ion at low concentration. The optical spectra of Al interstitial are calculated, and the results show that in the paraelectric and ferroelectric phases, the optical transition of Al ions generally produces a large lattice relaxation energy, such as the lattice relaxation energy of up to 4.00 eV in the +2 to +3 charged defect transition in the paraelectric phase. This shows that the optical transition of Al interstitial will cause serious damage to the crystal. In the paraelectric phase, the absorption peaks of optical transitions found in the ultraviolet and visible regions are consistent with experiments. The absorption peak of the +1 to +2 charged defect transition is at 260 nm, which is very close to the absorption peak at 270 nm measured by experiments. The analysis of the Huang-Rys factors and transition displacement further confirms the conclusion that the optical transition of the defect charged state will cause serious crystal damage.

Enhanced Fenton performance of wet-mechanochemically synthesized FeS2/Biochar: The multiple synergistic effect derived from mutual element doping

FeS2-biochar composites have been considered as promising heterogeneous Fenton materials for pollutants removal. However, the chemical synthesis of element-doped FeS2-biochar composite with superior performance and the comprehensive investigation for its underlying multiple synergistic mechanism remain a difficult endeavor. Herein, a novel FeS2/Biochar nanocomposite with mutual element doping was firstly synthesized by facile wet-mechanochemical method using iron, sulfur and bamboo-biochar for efficient organic pollutant (sulfamonomethoxine, SMM) removal. Experiment and DFT calculation results revealed that multiple synergistic effect between FeS2 and biochar derived from newly formed Fe-C and C-S-C bonds induced the abundant reactive oxygen species (ROS) and excellent electron transfer capacity. Fe-C sites facilitated the H2O2 adsorption and populated O-O bond in H2O2 for its barrierless dissociation into •OH via forming bridging C-Fe-O-O-Fe bond. Oxygen vacancy, C-S-C and Fe-C bonds, persistent free radicals (PFRs) accelerated the generation and transformation of ROS, which resulted in dominating free radical (•OH, •O2–, •SO4-) and auxiliary non-radical (1O2) pathway. Meanwhile, Fe3+/Fe2+ redox-cycle was expedited by electron donor/shuttle (S22-, BC, •O2–, C-S-C and Fe-C bonds). All these specialties contributed to the superior performance of FeS2/Biochar Fenton system for SMM removal at wide pH range (3–11) with negligible Fe release. Completely SMM (50 mg/L) removal was achieved within 20 min for 8 successive reuses. This work emphasized the concept of building mutual element doping on molecular level in enhancing FeS2-Biochar synergy towards efficient environmental remediation.

Two-dimensional molybdenum boride coordinating with ruthenium nanoparticles to boost hydrogen generation from hydrolytic dehydrogenation of ammonia borane

The coordination between carrier and active metal is critical to the catalytic efficiency of ammonia borane (AB) hydrolysis reaction. In the present study, we report a new type of catalytic support based on molybdenum boride (MBene) MoAl1-xB and demonstrate that the effective combination of MoAl1-xB with Ru nanoparticles can realize the significantly enhanced performance for hydrogen generation. Owing to the efficient activation and dissociation of reactants, the optimal Ru/MoAl1-xB catalyst achieves the large turnover frequency of 494 molH2 molRu-1 min−1, high hydrogen generation rate of 119817 mL min−1 gRu-1 and favorable apparent activation energy of 39.2 kJ mol−1 for the catalytic hydrolysis of AB under alkaline-free condition. The isotopic test suggests the cleavage of OH bond in H2O is the rate-determining step for hydrolysis reaction, while the fracture of B–H bond in AB is also well revealed by attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy. Significantly, the flexible on-demand hydrogen generation is achieved by using chemical switches for on–off AB hydrolysis. This study provides a new support platform based on two-dimensional MBene to exploit efficient catalysts to boost AB dehydrogenation.

Fluorine Modification Promoted Water Dissociation into Atomic Hydrogen on a Copper Electrode for Efficient Neutral Nitrate Reduction and Ammonia Recovery.

Electrocatalytic nitrate reduction to ammonia (NITRR) offers an attractive solution for alleviating environmental concerns, yet in neutral media, it is challenging as a result of the reliance on the atomic hydrogen (H*) supply by breaking the stubborn HO-H bond (∼492 kJ/mol) of H2O. Herein, we demonstrate that fluorine modification on a Cu electrode (F-NFs/CF) favors the formation of an O-H···F hydrogen bond at the Cu-H2O interface, remarkably stretching the O-H bond of H2O from 0.98 to 1.01 Å and lowering the energy barrier of water dissociation into H* from 0.64 to 0.35 eV at neutral pH. As a benefit from these advantages, F-NFs/CF could rapidly reduce NO3- to NH3 with a rate constant of 0.055 min-1 and a NH3 selectivity of ∼100%, far higher than those (0.004 min-1 and 9.2%) of the Cu counterpart. More importantly, we constructed a flow-through coupled device consisting of a NITRR electrolyzer and a NH3 recovery unit, realizing 98.1% of total nitrogen removal with 99.3% of NH3 recovery and reducing the denitrification cost to $5.1/kg of N. This study offers an effective strategy to manipulate the generation of H* from water dissociation for efficient NO3--to-NH3 conversion and sheds light on the importance of surface modification on a Cu electrode toward electrochemical reactions.

Percarbonate activation by N-doped polyethylene terephthalate (PET)-derived carbon: The role of vacancy and insights into the mechanism

Percarbonate-based advanced oxidation processes catalyzed by carbon materials from plastic waste are rarely reported and lack clarity in their mechanisms. We synthesized N-doped polyethylene terephthalate (PET)-derived carbon materials with surface areas of up to 2190.9 m2/g and nitrogen/oxygen vacancies via urea-assisted pyrolysis. These materials exhibited exceptional adsorption and catalytic activities in a Fenton-like reaction for tetracycline degradation. The N-doped PET-derived catalyst (NPETK-800) achieved a 95 % removal efficiency for tetracycline at 50 mg/L, attributed to synergistic adsorption and oxidation effects via sodium percarbonate activation. NPETK-800 underwent surface hydroxylation through the electrostatic adsorption of OH− from CO32− hydrolysis on N and O vacancies, and its hydroxylated surface converted the adsorption mode of H2O2 to a H-bonded structure. This mode favored cleaving the OH bond over the OO bond in H2O2, generating 1O2 and O2−, crucial for tetracycline degradation. This study unveils the pivotal role of vacancies in tuning the generation of reactive oxygen species in Fenton-like reactions.

Accelerated Fe(III)/Fe(II) cycle for ultrafast removal of acetaminophen by a novel W18O49 co-catalytic Fe3+/H2O2 fenton-like system

The traditional Fenton reaction always encounters the restriction that the solution pH needs to be strictly regulated, and Fe2+ is easy to self-decompose but not easy to regenerate. Fe3+ is relatively stable but its reaction with H2O2 is super-restricted. A novel strategy for the co-catalytic effect of W18O49 on the enhancement of Fe3+/H2O2 reaction activity was presented in this study. The W18O49/Fe3+/H2O2 system achieved a 94% acetaminophen (ACE) degradation rate within 5 min, which was much higher than the Fe3+/H2O2 system (48%), and W18O49 also showed excellent repeatability. Quenching experiment and ESR proved that the removal of ACE mainly depended on 1O2 (leading role) and •OH, which was different from the previously reported Fenton/Fenton-like system dominated by •OH. Accelerated Fe2+/Fe3+ cycling controlled by variational W4+/W6+ and intermediate •OH stabilization by oxygen vacancy for enhancing the breaking of O-O bond in H2O2 to produce more radicals was the dual driving force in the W18O49/Fe3+/H2O2 system for enhanced oxidation activity. The W18O49/Fe3+/H2O2 system has favorable tolerance to a wide range of pH and anions, which provides a feasible strategy for the practical application of the Fenton-like system.

Reshaping hydrogen bond network in aqueous-aprotic hybrid electrolyte to achieve highly selective ambient ammonia synthesis

Aqueous electrolytes are extensively applied in electrochemical nitrogen reduction reaction, while the overwhelming H2O always produce much protons, favoring the electron-stealing hydrogen evolution reaction (HER) and thus leaving the current ammonia synthesis much to be desired. Here, we propose an aqueous-aprotic hybrid electrolyte system by introducing trimethyl phosphate (TMP) as a cosolvent to achieve highly selective ammonia synthesis. TMP features higher Gutmann donors than that of H2O, preferring to serve as hydrogen bond (HB) acceptor and reshaping the HB network in the electrolyte. Molecular dynamics simulations suggest that, compared with H2O-H2O HB, the H2O-TMP HB exhibits longer lifetime and better stability. The intensified interaction between H2O and TMP weakens the interaction between H2O and H2O, which strengthens the O-H bond of H2O and makes it more difficult to be broken, thus greatly inhibiting the dissociation of H2O and leading to a suppressed HER activity. Correspondingly, a significantly improved NRR performance with a superior NH3 yield rate of 82.1 ± 2.7 μg h–1 mg–1 and an optimum Faradaic efficiency of 73.3 ± 2.7% is achieved in the H2O-TMP hybrid electrolyte, indicative of order of magnitude enhancement compared with that delivered in the conventional aqueous electrolyte.

Molecule aging induced by electron attacking

Here we propose a new concept of “molecule aging”: with some special treatment, a molecule could be “aged” by losing some unknown tiny particles or pieces from atoms in the molecule. Such “aging” or loss of unknown tiny particles does not change apparently its molecular structure or chemical composition, but some physicochemical properties could be changed irreversibly. We further confirm such “molecule aging” via a long-term electron attacking to age water (H2O) molecules. The IR spectra show no structural difference between the fresh water and the aged one, while the NMR spectra show that the electron attacking can decrease the size of water clusters. Such facts indicate that the electron attacking indeed can “affect” the structure of water molecule slightly but without damaging to its basic molecule frame. Further exploration reveals that the hydrogen evolution reaction (HER) activity of the aged water molecule is lower than the fresh water on the same Pt/C electrocatalyst. The density functional theory calculations indicate that the shortened O–H bond in H2O indeed can present lower HER activity, so the observed size decrease of water clusters from NMR probably could be attributed to the shortening of O–H bond in water molecules. Such results indicate significantly that the molecule aging can produce materials with new functions for new possible applications.

Desirable performance and mechanism of RuPd nanoalloys in catalyzing hydrolytic dehydrogenation of NH3BH3

The dehydrogenation of liquid-phase chemical hydrogen storage materials (such as ammonia borane, AB, NH3BH3) is a promising strategy to develop the promising hydrogen economy. Considering that the self-hydrolysis of AB is nearly impossible at room temperature, it is very worthwhile to search a robust catalyst for this hydrolytic reaction and clarify the catalytic mechanism. In this work, a glucose-derived N/O co-doped and multi-level porous carbon (marked as g-pC, SBET = 1356 m2 g−1, Vtotal = 0.762 cm3 g−1, Smicro = 1079 m2 g−1, Vmicro = 0.427 cm3 g−1) is prepared for confining RuPd alloys. Benefitting from the positive effect of g-pC (such as the particular anchoring and geometric effects on highly and tightly confining RuPd nanoparticles, as well as enhanced hydrophilicity) and the exceptional metal alloy effect, the obtained bimetallic catalysts unveil drastically enhanced catalytic activity in AB hydrolysis compared to the monometallic counterparts. Especially, catalyzed by the optimal Ru0.25Pd0.75@g-pC with a mean alloy size of 1.5 nm (10 mg), the dehydrogenation of 1.00 mmol AB can be finished within 1 min at 303 K in NaOH solution (1.5 M). The corresponding turnover frequency and hydrogen generation rate are calculated to be 541.09 min−1 and 145,950 mL min−1 g−1, respectively. Moreover, about 62% of the initial catalytic activity is still retained even in the 18th cyclic experiment, suggesting the extraordinarily long durability. In addition, the isotopic analyses present a kinetic isotope effect (KIE) of 3.38, further confirming that the scission of an O-H bond in H2O is the rate-controlling step in this hydrolytic reaction. Our work offers a competitive metal alloy catalyst for generating hydrogen from AB aqueous solution and promote the development and safety utilization of hydrogen energy.

Trehalose in Trace Quantities as a Multifunctional Electrolyte Additive for Highly Reversible Zinc Metal Anodes.

The unsatisfactory performance of Zn metal anodes significantly impedes the commercial application of aqueous zinc-ion batteries (AZIBs). Herein, we introduce a trace amount of a multifunctional trehalose additive to enhance the stability and reversibility of Zn metal anodes. The trehalose additive exhibits a stronger Zn2+ ion affinity due to abundant lone-pair electrons, disrupting hydrogen bonds in H2O, regulating solvation structures, and tuning the Zn-electrolyte interface. Consequently, the Zn metal anode demonstrates a remarkable Coulombic efficiency of 99.80% and a cycle stability exceeding 4500 h at 1 mA cm-2. Even under stringent conditions of 10 mA cm-2, the Zn metal anode maintains a cumulative capacity of 2500 mA h cm-2 without a short circuit. Furthermore, Zn//Zn symmetric batteries exhibit excellent low-temperature cycle performance (over 400 h at -10 °C). As a proof of concept, assembled Zn//NH4V4O10 and Zn//MnO2 pouch cells demonstrate an improved electrochemical performance. This work presents an electrolyte additive strategy for achieving stable zinc anode operation in AZIBs.

Controllable hydrogen release from NH3BH3 hydrolysis over Ru ultrafine particles stabilized on agriculture waste-derived carbon

Simultaneously considering cost, safety and catalytic efficiency, the development of a cost-effective and high-performance catalyst is significant and challenging for controllable hydrogen release from ammonia borane (AB, NH3BH3) hydrolysis. In this work, Ru ultrafine particles are evenly and firmly stabilized on wheat straw-derived porous carbon through a facile procedure. Specifically, attributed to the abundant co-doping of heteroatoms (namely, N and O) and suitable hierarchical porous structure of WSC-1.0 with large specific surface area (1000 m2 g−1), which is prepared with a mass ratio of 1: 1 for K2CO3 to the pre-carbonized biomass waste, as well as high dispersion (32.6%) of Ru ultrafine particles with an average size of 1.4 ± 0.3 nm, the optimal Ru/WSC-1.0 displays exceptional catalytic performance in the hydrolysis of AB. The corresponding turnover frequency (TOF) and specific reaction rate (rB) are 167.7 min−1 and 4.07 × 104 mL min−1 gRu−1, respectively, and the apparent activation energy is 40.94 kJ mol−1. Upon adding NaOH (1.0 M), the hydrolysis rate can be remarkably accelerated (TOF = 401.4 min−1, rB = 9.75 × 104 mL min−1 gRu−1). The isotope experiments show that the scission of an O-H bond in H2O by oxidative addition is the decisive step in this reaction. Impressively, the effective “on-off” control for the hydrolytic dehydrogenation reaction over Ru/WSC-1.0 can be easily realized by introducing certain amounts of Zn(NO3)2 and EDTA-2Na, separately. Our work delivers a facile approach for efficient utilization of agricultural wastes and offers a robust and cost-effective catalyst for the controllable hydrogen evolution from AB hydrolysis.

Engineering eutectic network for regulating the stability of polyiodides towards high rate and long cycling zinc-iodine batteries

Despite aqueous Zn-iodine batteries have gained enormous research interests, their development is restricted by disproportionation and diffusion of polyiodides. Herein, for the first time, we propose a distinct electrolyte engineering strategy for regulating the performance of Zn-iodine batteries. A hydrated eutectic electrolyte composed of zinc tetrafluoroborate hydrate (ZBF) and succinonitrile (SN) forms the unique SNH2O eutectic network, which breaks the H2OH2O hydrogen network, strengthens OH bond in H2O and constrains the freedom of water molecules. Consequently, the disproportionation and diffusion of polyiodides are suppressed. The investigation for the solvation structure based on the spectroscopy results and molecular dynamics simulations demonstrate the relatively weak solvation effect of the organic ligand SN with Zn2+, which enables superior ion conductivity and high transference number. As a result, the as-assembled Zn-iodine battery based on optimized eutectic electrolyte delivers a high capacity of 202 mAh g−1 at 0.5 A g−1 with 99.5% coulombic efficiency, superior rate performance (capacity retention of 60% at 20 A g−1) and outstanding cycling stability (over 10,000 cycles). Benefiting from its anti-freezing ability, the hydrated eutectic electrolyte enables Zn-iodine battery to work stably at a low-temperature of -20°C. The paradigm provides an encouraging strategy to construct the stable aqueous Zn-halogen batteries through electrolyte engineering.