Promoting the Direct H2O2 Generation Catalysis by Using Hollow Pd–Sn Intermetallic Nanoparticles

Although direct hydrogen (H₂) oxidation to hydrogen peroxide (H₂O₂) is considered as a promising strategy for direct H₂O₂ synthesis, the desirable conversion efficiency remains formidable challenge. Herein, highly active and selective direct H₂ oxidation to H₂O₂ is achieved by using hollow Pd–Sn intermetallic nanoparticles (NPs) as the catalysts. By tuning the catalytic solvents and catalyst supports, the efficiency of direct H₂ oxidation to H₂O₂ can be optimized well with the hollow Pd₂Sn NPs/P25 exhibiting H₂O₂ selectivity up to 80.7% and productivity of 60.8 mol kg_cat^?1 h^?1. In situ diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption results confirm the different surface atom arrangements between solid and hollow Pd–Sn NPs. X‐ray photoelectron spectra results show that the higher efficiency of Pd₂Sn NPs/P25 is due to its higher content of metallic Pd and higher ratio of Sn^x+, which benefit H₂O₂ production and selectivity.     

A Robust Molecular Porous Material for C2H2/CO2 Separation

A molecular porous material, MPM-2, comprised of cationic [Ni₂(AlF₆)(pzH)₈(H₂O)₂] and anionic [Ni₂Al₂F₁₁(pzH)₈(H₂O)₂] complexes that generate a charge-assisted hydrogen-bonded network with pcu topology is reported. The packing in MPM-2 is sustained by multiple interionic hydrogen bonding interactions that afford ultramicroporous channels between dense layers of anionic units. MPM-2 is found to exhibit excellent stability in water (>1 year). Unlike most hydrogen-bonded organic frameworks which typically show poor stability in organic solvents, MPM-2 exhibited excellent stability with respect to various organic solvents for at least two days. MPM-2 is found to be permanently porous with gas sorption isotherms at 298 K revealing a strong affinity for C₂H₂ over CO₂ thanks to a high (ΔQ_st)_AC [Q_st (C₂H₂) − Q_st (CO₂)] of 13.7 kJ mol⁻¹ at low coverage. Dynamic column breakthrough experiments on MPM-2 demonstrated the separation of C₂H₂ from a 1:1 C₂H₂/CO₂ mixture at 298 K with effluent CO₂ purity of 99.995% and C₂H₂ purity of >95% after temperature-programmed desorption. C-H···F interactions between C₂H₂ molecules and F atoms of AlF₆³⁻ are found to enable high selectivity toward C₂H₂, as determined by density functional theory simulations.     

Hydrogen substitutes for the in situ generation of H2O2: an application in the Fenton reaction

This study investigates the ability of formic acid, hydrazine and hydroxylamine to act as H₂ substitutes in conducting phenol degradation by Fenton reaction using in situ generated hydrogen peroxide. The processes were performed with semi-heterogeneous (Pd/Al₂O₃ + soluble Fe²⁺) and fully heterogeneous (FePd/Al₂O₃) catalytic systems under ambient conditions. In contrast to bulk H₂O₂ production conditions, hydrazine is able to produce H₂O₂in situ followed by phenol degradation using Pd/Al₂O₃ + Fe²⁺ at pH 3 without the need for halide ions. However, a degree of mineralization exceeding 37% could not be achieved. The significant production of in situ H₂O₂ at the inherent acidic pH of hydroxylammonium sulfate in the presence of Pd/Al₂O₃ + Fe²⁺ was also found to differ from the bulk production of H₂O₂, in which no H₂O₂ was detected. A remarkable degree of mineralization (ca. 65%) as well as fast phenol degradation during the reaction started at pH 7 over FePd/Al₂O₃ may be an advantage of using hydroxylamine. On the other hand, using formic acid, H₂O₂ was produced at a moderate rate, thereby achieving higher efficiency in the mineralization of phenol. Most importantly, the catalysts were more stable in the presence of formic acid than hydrazine or hydroxylamine.     

Precise Pore Engineering of fcu-Type Y-MOFs for One-Step C2H4 Purification from Ternary C2H6/C2H4/C2H2 Mixtures

The purification of C₂H₄ from C₂H₆/C₂H₄/C₂H₂ mixtures is of great significance in the chemical industry for C₂H₄ production but remains a daunting task. Guided by powerful reticular chemistry principles, herein a systematic study is carried out to engineer pore dimensions and pore functionality of fcu-type Y-based metal–organic frameworks (Y-MOFs) through the construction of a series of eight new structures using linear dicarboxylate linkers with different length and functional groups. This study illustrates how delicate changes in pore size and pore surface chemistry can effectively influence the adsorption preference of C₂H₆, C₂H₄, and C₂H₂ by the MOFs. Importantly, clear relations between pore size/pore surface polarity and C₂ adsorption selectivities of this series of MOFs are established. In particular, HIAM-326 built on a linker decorated with trifluoromethoxy group shows notably preferential adsorption of C₂H₆ and C₂H₂ over C₂H₄, with balanced C₂H₂/C₂H₄ and C₂H₆/C₂H₄ selectivities. This endows the compound with the capability of one-step purification of C₂H₄ from C₂H₆/C₂H₄/C₂H₂ ternary mixtures, which is validated by breakthrough measurements where high purity C₂H₄ (99.9%+) can be obtained directly from the separation column. Its adsorption thermodynamics and underlying selective adsorption mechanisms are further revealed by ab initio calculations.     

Synthesis of SiO2 glass fibres from Si(OC2H5)4-H2O-C2H5OH-HCl solutions through sol-gel method

Various factors affecting the spinnability of the Si(OC₂H₅)₄-H₂O-C₂H₅OH-HCl solutions have been investigated in order to find appropriate experimental conditions for making gel-derived SiO₂ glass fibres. The molar ratios of H₂O, C₂H₅OH and HCl to Si(OC₂H₅)₄ were changed in the range from 0.5 to 10.0, 0.5 to 7.0 and 0.001 to 0.1, respectively. The solutions were reacted at 30 and 80° C. It has been reconfirmed that the most important factor determining the spinnability of the solution in the course of the hydrolysis reaction is the molar ratio of water to Si(OC₂H₅)₄ in the solution. The rise of the reaction temperature led to the remarkable shortening of the time required for drawing fibres. The increase of the amount of HCl decreased the upper limit of the H₂O/Si(OC₂H₅)₄ molar ratio range where the spinnability is found as well as reaction temperature. The solutions with a H₂O/Si(OC₂H₅)₄ ratio larger than 2.0 gave often fibres having a circular cross-section, while other solutions gave fibres with a non-circular one. The tensile strength of the gel-derived SiO₂ glass fibres was also reported.     

Effect of a hydrogen (H2)‐enriched solution on the albumin redox of hemodialysis patients

Elevated oxidative stress (OS) is associated with severe cardiovascular disease and premature death among patients treated with hemodialysis (HD). Oxidative stress is enhanced by contact between blood and dialysis membranes during HD sessions. This study aimed to clarify whether hydrogen (H₂), which is a known antioxidant, is capable of suppressing increased OS induced during HD sessions. Eight patients on regular HD treatment were studied. Two HD sessions were performed in a cross‐over design trial using standard and hydrogen‐enriched solutions (mean of 50 p.p.b. H₂; H₂‐HD). Blood samples were obtained from the inlet and outlet of the dialyzer during HD to determine changes in plasma levels of glutathione, hydrogen peroxide, and albumin redox state as a marker of OS. Comparison of inlet and outlet blood revealed significant decreases in total glutathione and reduced glutathione, as well as significant increases in hydrogen peroxide in both HD treatments. However, the mean proportion of reversibly oxidized albumin in outlet serum was significantly lower than that in inlet serum following the H₂‐HD session, whereas no significant changes were found in the standard solution session, suggesting that “intra‐dialyzer” OS is reduced by H₂‐HD. In conclusion, the application of H₂‐enriched solutions could ameliorate OS during HD.     

H atoms in CH4 and Xe matrices at cryogenic temperatures

Cryogenic techniques coupled with electron spin resonance detection methods have made it possible to produce long-lived trapped hydrogen atoms in inert matrices at 4 K and to study their reactions with neutral molecules and molecular fragments when the temperature is raised to the point where they diffuse. Under the matrix conditions H atoms abstract H rapidly from all carbon-hydrogen bonds (except those of CH₄) by quantum mechanical tunnelling, even though such reactions would be precluded if the classical activation energy prevailed. Thermal H atoms in CH₄ at 15 K add to CO to form the HCO radical, and to O₂ to form the HO₂ radical. When exposed to the appropriate wavelength of light these and other radicals, including CH₃, C₂H₅ and C₂H₃ lose H by photoelimination. The H atoms are produced in the matrices by X radiolysis, γ-ray radiolysis, or photolysis of a hydrogen halide. This paper reviews some of the most significant current findings in the field from different laboratories.     

Equation of State of He-H2 and He-D2 Dense Fluid Mixtures at High Pressures and Temperatures

The fluid variational theory is used to calculate the Hugoniot equation of state (EOS) of He, D₂, He + H₂, and He + D₂ fluid mixtures with different He:H₂ and He:D₂ compositions at high pressures and temperatures. He, H₂, and D₂ are the lightest elements. Therefore, the quantum effect is included via a first-order quantum correction in the framework of the Wigner-Kirkwood expansion. An examination of the reliability of the above computations is performed by comparing experiments and calculations, in which the calculation procedure used for He and D₂ is adopted also for He + D₂ and He + H₂, since no experimental data for the mixtures are available to conduct these comparisons. Good agreement in both comparisons is found. This result may be seen as an indirect verification of the calculation procedures used here, at least, in the pressure and temperature domains covered by the experimental data for He and D₂ used for comparisons, which is nearly up to 40 GPa and 10⁵ K. Also, the equation of state of He + H₂ fluid mixtures with different compositions is predicted over a wide range of temperatures and pressures.     

Specific Features of Anodic Dissolution of Copper in H2SO4 + H2O and H2SO4 + CuSO4 + H2O Systems

We investigate anodic dissolution of copper in H₂SO₄ + H₂O and H₂SO₄ + H₂O + CuSO₄ systems, which model solutions for the electrochemical production of copper (+2) sulfate. Ultimate densities of anodic current in the temperature range 20–80°C for a voltage up to 8 V were found. We show that a concentration of copper ions ( Cu²⁺) of 1.5–2.0 moles/liter in the anolyte is the limiting one in the electrochemical production of solutions of copper (+2) sulfate.     

Spatial Specific Janus S-Scheme Photocatalyst with Enhanced H2O2 Production Performance

Photocatalytic oxygen reduction reaction (ORR) for H₂O₂ production in the absence of sacrificing agents is a green approach and of great significance, where the design of photocatalysts with high performance is the central task. Herein, a spatial specific S-scheme heterojunction design by introducing a novel semiconducting pair with a S-scheme mechanism in a purpose-designed Janus core–shell-structured hollow morphology is reported. In this design, TiO₂ nanocrystals are grown inside the inner wall of resorcinol-formaldehyde (RF) resin hollow nanocakes with a reverse bumpy ball morphology (TiO₂@RF). The S-scheme heterojunction preserves the high redox ability of the TiO₂ and RF pair, the spatial specific Janus design enhances the charge separation, promotes active site exposure, and reduces the H₂O₂ decomposition to a large extent. The TiO₂@RF photocatalyst shows a high H₂O₂ yield of 66.6 mM g⁻¹ h⁻¹ and solar-to-chemical conversion efficiency of 1.11%, superior to another Janus structure (RF@TiO₂) with the same heterojunction but a reversed Janus spatial arrangement, and most reported photocatalysts under similar reaction conditions. The work has paved the way toward the design of next-generation photocatalysts for green synthesis of H₂O₂ production.     

H2S‐Scavenged and Activated Iron Oxide‐Hydroxide Nanospindles for MRI‐Guided Photothermal Therapy and Ferroptosis in Colon Cancer

Overproduced hydrogen sulfide (H₂S) is of vital importance for the progress of colon cancer and promotes cancer cellular proliferation. Devising pharmacological nanomaterials for tumor‐specific H₂S activation will be significant for precise colon cancer treatment. Herein, a biocompatible fusiform iron oxide‐hydroxide nanospindles (FeOOH NSs) nanosystem for magnetic resonance imaging (MRI), ferroptosis, and H₂S based cascade reaction‐enhanced combinational colon cancer treatment is developed. The FeOOH NSs can effectively scavenge endogenous H₂S via the reduction reaction to prohibit the growth of CT26 colon cancer. The cascade produced FeS driven by overexpressed H₂S exhibits near‐infrared‐triggered photothermal therapy capability and Fe²⁺‐mediated ferroptosis functionality. Meanwhile, the as‐prepared FeOOH NSs can light up tumor tissues as a potent MRI contrast agent. Additionally, FeOOH NSs present desirable biosafety in a murine model for up to three months and avoid any long‐term toxicity. Furthermore, it is found that these H₂S‐responsible nanotheranostics do not cause any cure effects on other cancer types, such as 4T1 breast cancer. Overall, the findings illustrate that the biocompatible FeOOH NSs can be successfully employed as a theranostic for specifically treating colon cancer, which may promote the clinical translation and development of H₂S‐responsive nanoplatforms.     

Synthesis and structural study of new potassium uranyl selenates K2(H5O2)(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)4 and K3(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)5

Single crystals of new uranyl selenates K₂(H₅O₂)(H₃O)[(UO₂)₂(SeO₄)₄(H₂O)₂](H₂O)₄ (1) and K₃(H₃O)[(UO₂)₂(SeO₄)₄(H₂O)₂](H₂O)₅ (2) were prepared by isothermal evaporation at room temperature. The crystal structure of 1 was solved by the direct method [C2/c, a = 17.879(5), b = 8.152(5), c = 17.872(5) Å, β = 96.943(5)°, V = 2585.7(19) ų, Z = 4] and refined to R ₁ = 0.0449 (wR ₂ = 0.0952) for 2600 reflections with |F _o| ≥ 4σ _F . The structure of 2 was solved by the direct method [P2₁/c, a = 17.8377(5), b = 8.1478(5), c = 23.696(1) Å, β = 131.622(2)°, V = 2574.5(2) ų, Z = 4] and refined to R ₁ = 0.0516 (wR ₂ = 0.1233) for 4075 reflections with |F _o| ≥ 4σ _F . The structures of 1 and 2 are based on [(UO₂)₂(SeO₄)₄(H₂O)₂]^4? layers. The charge of the inorganic layer is compensated by potassium and oxonium ions arranged in the interlayer space. Each K ion is surrounded by seven O atoms belonging to uranyl selenate layers and water molecules, so that it binds with each other the adjacent uranyl selenate structural elements.     

Metal‐Free 2D/2D Phosphorene/g‐C3N4 Van der Waals Heterojunction for Highly Enhanced Visible‐Light Photocatalytic H2 Production

The generation of green hydrogen (H₂) energy using sunlight is of great significance to solve the worldwide energy and environmental issues. Particularly, photocatalytic H₂ production is a highly promising strategy for solar‐to‐H₂ conversion. Recently, various heterostructured photocatalysts with high efficiency and good stability have been fabricated. Among them, 2D/2D van der Waals (VDW) heterojunctions have received tremendous attention, since this architecture can promote the interfacial charge separation and transfer and provide massive reactive centers. On the other hand, currently, most photocatalysts are composed of metal elements with high cost, limited reserves, and hazardous environmental impact. Hence, the development of metal‐free photocatalysts is desirable. Here, a novel 2D/2D VDW heterostructure of metal‐free phosphorene/graphitic carbon nitride (g‐C₃N₄) is fabricated. The phosphorene/g‐C₃N₄ nanocomposite shows an enhanced visible‐light photocatalytic H₂ production activity of 571 µmol h^?1 g^?1 in 18 v% lactic acid aqueous solution. This improved performance arises from the intimate electronic coupling at the 2D/2D interface, corroborated by the advanced characterizations techniques, e.g., synchrotron‐based X‐ray absorption near‐edge structure, and theoretical calculations. This work not only reports a new metal‐free phosphorene/g‐C₃N₄ photocatalyst but also sheds lights on the design and fabrication of 2D/2D VDW heterojunction for applications in catalysis, electronics, and optoelectronics.     

Sulfur-Induced Low Crystallization of Ultrathin Pd Nanosheet Arrays for Sulfur Ion Degradation-Assisted Energy-Efficient H2 Production

The utilization of thermodynamically favorable sulfur oxidation reaction (SOR) as an alternative to sluggish oxygen evolution reaction is a promising technology for low-energy H₂ production while degrading the sulfur source from wastewater. Herein, amorphous/crystalline S-doped Pd nanosheet arrays on nickel foam (a/c S-Pd NSA/NF) is prepared by S-doping crystalline Pd NSA/NF.  Owing to the ultrathin amorphous nanosheet structure and the incorporation of S atoms, the a/c S-Pd NSA/NF provides a large number of active sitesand the optimized electronic structure, while exhibiting outstanding electrocatalytic activity in hydrogen evolution reaction (HER) and SOR. Therefore, the coupling system consisting of SOR-assisted HER can reach a current density of 100 mA cm⁻² at 0.642 V lower than conventional electrolytic water by 1.257 V, greatly reducing energy consumption. In addition, a/c S-Pd NSA/NF can generate H₂ over a long period of time while degrading S²⁻ in water to the value-added sulfur powder, thus further reducing the cost of H₂ production. This work proposes an attractive strategy for the construction of an advanced electrocatalyst for H₂ production and utilization of toxic sulfide wastewater by combining S-doping induced partial amorphization and ultrathin metal nanosheet arrays.     

Synthesis of nanotube from a layered H2Ti4O9 · H2O in a hydrothermal treatment using various titania sources

In this paper, the synthesis of tubular titania was carried out through a soft chemical hydrothermal reaction of TiO₂ powders in NaOH or KOH aqueous solution systems. It was found that nanotubular products prepared in our studies were identified as H₂Ti₄O₉·H₂O by X-ray diffraction analysis with their morphology and crystallinity being dependent on synthetic conditions, i.e. reaction time and temperature of the hydrothermal process. The photocatalytic activity of nanotubular H₂Ti₄O₉·H₂O was evaluated in a decomposition test of HCHO at 298 K in an aqueous system using radiation with a mercury lamp. The morphology and yield of these nanotubular products were found to be dependent on the hydrothermal synthetic conditions.     

Construction of ZnIn2S4/CdS/PdS S-Scheme Heterostructure for Efficient Photocatalytic H2 Production

It is facing a tremendous challenge to develop the desirable hybrids for photocatalytic H₂ generation by integrating the advantages of a single semiconductor. Herein, an all-sulfide ZnIn₂S₄/CdS/PdS heterojunction is constructed for the first time, where CdS and PdS nanoparticles anchor in the spaces of ZnIn₂S₄ micro-flowers due to the confinement effects. The morphology engineering can guarantee rapid charge transfer owing to the short carrier migration distances and the luxuriant reactive sites provided by ZnIn₂S₄. The S-scheme mechanism between ZnIn₂S₄ and CdS assisted by PdS cocatalyst is testified by in situ irradiated X-ray photoelectron spectroscopy and electron paramagnetic resonance (EPR), where the electrons and holes move in reverse driven by work function difference and built-in electric field at the interfaces. The optimal ZnIn₂S₄/CdS/PdS performs a glaring photocatalytic activity of 191.9 µmol h⁻¹ (10 mg of catalyst), and the largest AQE (apparent quantum efficiency) can reach a high value of 26.26%. This work may afford progressive tactics to design multifunctional photocatalysts.     

The role of the rotational state in intermolecular interactions of H2O with H2 and CH3Cl

Rotational-state resolved measurements of H₂O−H₂ and H₂O−CH₃Cl intermolecular interactions were performed. Using light-induced drift as a tool, we measured changes in transport collision ratev upon rovibrational (J, r)-excitation of H₂O. We studied P- and R-branch excitation withJ ranging from O through 9 for H₂O excited in the fundamental asymmetric stretch mode. Combination of P and R data yields the dependencies ofv upon rotational (J) and vibrational (r) quantum numbers separately. For H₂O−CH₃Cl it is found thatv decreases by 25% asJ increases from 0 to 9. For H₂O−H₂ the decrease is only 1.0%. These data seem to exemplify a fundamental aspect of dipole-dipole interaction: the familiar 1r ³ interaction term is highlyJ-dependent. This is attributed to the increasing averaging-out of the dipolar potential as the rotational quantum number increases. Paper dedicated to Professor Edward A. Mason.     

Sulphidation and oxidation of the Ni22Cr10Al1Y alloy in H2/H2S and SO2 atmospheres at high temperatures

The Ni22Cr10Al1Y alloy was exposed in H₂/H₂S gas mixture under the sulphur pressure 10^–3 and 1 Pa as well as in SO₂ at 1173 and 1273 K. At p_s = 1 Pa the sulphidation rate was relatively high and the reaction obeyed the linear rate law. Under these conditions a nickel/nickel sulphide eutectic was formed. At p_s = 10^–3 Pa nickel sulphides became unstable and the sulphidation rate was significantly lower. The reaction obeyed the parabolic rate law. The oxidation rate of the alloy in SO₂ was lower than that in any of the H₂/H₂S atmospheres. The sulphide scales formed during sulphidation in H₂/H₂S had complex microstructures and compositions, with sulphospinel and sulphide phases being present, e.g. NiCr₂S₄, Ni₃S₂, Cr_xS_y. As the temperature increased and the sulphur pressure decreased, these phases were replaced by the chromium-rich sulphide phase. Various oxides formed during oxidation of the alloy in SO₂.     

Photoassisted fabrication of zinc indium oxide/oxysulfide composite for enhanced photocatalytic H2 evolution under visible-light irradiation

A photoassisted approach has been developed to synthesize a zinc indium oxide (Zn₅In₂O₈)/oxysulfide composite through in situ sulfuration of vacancy-rich Zn₅In₂O₈. It was found that vacancies have a considerable impact on the formation of the composite. The composite exhibited an increased photocatalytic H₂ evolution activity under visible-light irradiation, which probably resulted from the enhanced ability to separate photoinduced electrons and holes. The H₂ evolution rate over the composite was about 17 times higher when using vacancy-rich rather than conventional Zn₅In₂O₈. This study provides a new method of improving the activity of photocatalysts.     

Efficient Polysulfide‐Based Nanotheranostics for Triple‐Negative Breast Cancer: Ratiometric Photoacoustics Monitored Tumor Microenvironment‐Initiated H2S Therapy

The incidence of triple‐negative breast cancer (TNBC) is difficult to predict, and TNBC has a high mortality rate among women worldwide. In this study, a theranostics approach is developed for TNBC with ratiometric photoacoustic monitored thiol‐initiated hydrogen sulfide (H₂S) therapy. The ratiometric photoacoustic (PA) probe (CY) with a thiol‐initiated H₂S donor (PSD) to form a nanosystem (CY‐PSD nanoparticles) is integrated. In this theranostics approach, H₂S generated from PSD is sensed by CY based on ratiometric PA signals, which simultaneously pinpoints the tumor region. Additionally, H₂S is cytotoxic toward TNBC cells (MDA‐MB 231), showing a tumor inhibition rate of 63%. To further verify its pharmacological mechanism, proteomics analysis is performed on tumors treated with CY‐PSD nanoparticles. Cells are killed by the significant mitochondrial dysfunction via supressed energy supply and apoptosis initiation. Besides, the observed inhibition of oxidative stress also generates the cytotoxicity. Significant Kyoto Encyclopedia of Genes Genomes pathways related to TNBC are found to be inhibited. This H₂S theranostics approach updates the current anticancer therapies which brings promise for women suffering malignant breast cancer.