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The hydrogenation of metal nanoparticles provides a pathway toward tuning their combustion characteristics. Metal hydrides have been employed as solid-fuel additives for rocket propellants, pyrotechnics, and explosives. Gas generation during combustion is beneficial to prevent aggregation and sintering of particles, enabling a more complete fuel utilization. Here, we discuss a novel approach for the synthesis of magnesium hydride nanoparticles based on a two-step aerosol process. Mg particles are first nucleated and grown via thermal evaporation, followed immediately by in-flight exposure to a hydrogen-rich low-temperature plasma. During the second step, atomic hydrogen generated by the plasma rapidly diffuses into the Mg lattice, forming particles with a significant fraction of MgH2. We find that hydrogenated Mg nanoparticles have an ignition temperature that is reduced by ∼200 °C when combusted with potassium perchlorate as an oxidizer, compared to the non-hydrogenated Mg material. This is due to the release of hydrogen from the fuel, jumpstarting its combustion. In addition, characterization of the plasma processes suggests that a careful balance between the dissociation of molecular hydrogen and heating of the nanoparticles must be achieved to avoid hydrogen desorption during production and achieve a significant degree of hydrogenation. more...

To the best of our knowledge, there are no studies on the effects of molecular hydrogen (H2) on microorganisms. In this study, we performed co-culture experiments using two microorganisms involved in sake brewing: sake yeast strain K1401 and the kuratsuki bacterium Kocuria strain TGY1127_2. The cells were suspended in water or water containing H2 and statically incubated at 4 °C for 2 h before co-culture. Sake taste was estimated using a taste sensor. The taste of sake was affected by H2 treatment of kuratsuki Kocuria as well as sake yeast. These results strongly suggest that H2 treatment alters the physiology of kuratsuki bacteria and sake yeast. We showed that sake undergoes H2 treatment of the microorganisms involved in sake brewing to boost its variety and meet the market demand. [ABSTRACT FROM AUTHOR] more...

Nanoparticlesof tungsten oxide combined with varying amounts of gadolinium ions were synthesised by a hydrochloric acid-assisted precipitation method. The powders were characterised by ; X-ray fluorescence (XRF), X-ray diffraction (XRD), diffuse reflectance (DRS), and magnetic measurements. The ordinary monoclinic structure of WO3 was transformed into one of its Magneli structures (W32O84) by the incorporation of a tiny Gd ions due to the variation in the local charge neutrality. Different magnetic behaviours of Gd-incorporated W-oxide were observed depending on the synthesis procedure including a hydrogenation. The hydrogenated Gd-incorporated W-oxide has FM-behaviour. However, the created FM properties were severely undermined by increasing the Gd inclusion to more than 1%, which was attributed to the effect of the Gd interionic separations and the minute solubility of Gd in of W-oxide. This study focuses on the conditions necessary to realise the creation of FM in W-oxide by Gd ions incorporation for many applications, such as optical phosphors and catalysts. [ABSTRACT FROM AUTHOR] more...

This work is devoted to the effect of pulse hydrogen saturation on a gold film on glass used as a surface plasmon resonance sensor of the "Plasmon-6" spectrophotometer. Due to electrolysis in a 10 % solution of H2SO4 in water, the film was saturated with hydrogen. The surface of the gold film was the cathode, and the carbon electrode was the anode. Electrolysis current pulses lasted 2 s when the time interval between pulses was 1800 s. In this way, several samples were processed. The consequences of the action of five, ten, fifteen and twenty pulses on a gold film were examined as the experimentally obtained spectral curves for treated samples. The surface plasmon resonance is sensitive to changes occurring in the surface layer of the surface plasmon resonance sensor. It is applicable to control and analyze the changes induced by the proposed hydrogen treatment. In the experiments, the plasmon resonance curves shifted to larger angles. Therefore the optical properties modifications of the surface layer of the gold film were recorded. The observed changes gradually increased with the increase of the number of pulses of the electrolysis current. The mathematical approach to light reflection from the gold film was performed to analyze changes in the surface layer of the gold film. The dielectric properties of the surface layer of the gold film were estimated using the effective medium model. It made it possible to simulate changes in the surface layer of the film induced by hydrogen treatment. As a result, theoretical curves of plasmon resonance were obtained. A qualitative correlation between the experimentally observed changes and the theoretical ideas about the processes occurring during hydrogen treatment in the surface layer of the gold film on glass was achieved. [ABSTRACT FROM AUTHOR] more...

Herein, first, we synthesize a multifunctional photocatalyst via metal oxides loaded (Co/Pd) on acid-treated TiO2 nanorods (ATO) and further introduce hydrogen annealing treatment. The hydrogen annealing treatment introduces metal oxides converted into a bimetallic form and delays the photogenerated charge recombination process. Also, oxygen vacancies are formed due to the partial reduction of Ti4+ to Ti3+ sites. In addition, oxygen vacancies help to improve photocatalytic degradation and antibacterial activity. The hydrogen-treated photocatalyst (Pd(1)-Co(1)/ATO (red)) demonstrates high degradation efficiencies of 99.63 and 99.90% (180 min) for orange II dye and BPA degradation, respectively, and an antibacterial activity of 97.00% (120 min) under one sun irradiation. In the photocatalytic removal of abiotic pollutants and live bacteria, the trapping experiment suggests that radical species (•O2– and •OH), assisted by photoinduced holes, are responsible for the high activities. The photoelectrochemical performance and time-resolved PL (TRPL) study illustrate that Pd(1)-Co(1)/ATO (red) reveals superior photoelectrochemical charge separation (electron–hole), lower resistance, and shorter lifetime (τ1 = 0.40 ns) as a photocatalyst. Finally, plausible charge transport mechanisms are proposed for the photocatalytic degradation of organic dye and bacterial disinfection over the Pd(1)-Co(1)/ATO (red) photocatalyst. [ABSTRACT FROM AUTHOR] more...

Abstract In this work, three GaN-based multiple quantum well (MQW) samples are grown to investigate the growth techniques of high-quality MQWs at low temperature (750 °C). Instead of conventional temperature ramp-up process, H2/NH3 gas mixture was introduced during the interruption after the growth of InGaN well layers. The influence of hydrogen flux was investigated. The cross-sectional images of MQW via transmission electron microscope show that a significant atomic rearrangement process happens during the hydrogen treatment. Both sharp interfaces of MQW and homogeneous indium distribution are achieved when a proper proportion of hydrogen was used. Moreover, the luminescence efficiency is improved strongly due to suppressed non-radiative recombination process and a better homogeneity of MQWs. Such kind of atomic rearrangement process is mainly caused by the larger diffusion rate of gallium and indium adatoms in H2/NH3 mixed gas, which leads to a lower potential barrier energy to achieve thermodynamic steady state. However, when excessive hydrogen flux is introduced, the MQW will be partly damaged, and the luminescence performance will deteriorate. more...

To the best of our knowledge, there are no studies on the effects of molecular hydrogen (H2) on microorganisms. In this study, we performed co-culture experiments using two microorganisms involved in sake brewing: sake yeast strain K1401 and the kuratsuki bacterium Kocuria strain TGY1127_2. The cells were suspended in water or water containing H2 and statically incubated at 4 °C for 2 h before co-culture. Sake taste was estimated using a taste sensor. The taste of sake was affected by H2 treatment of kuratsuki Kocuria as well as sake yeast. These results strongly suggest that H2 treatment alters the physiology of kuratsuki bacteria and sake yeast. We showed that sake undergoes H2 treatment of the microorganisms involved in sake brewing to boost its variety and meet the market demand. more...

In this work, three GaN-based multiple quantum well (MQW) samples are grown to investigate the growth techniques of high-quality MQWs at low temperature (750 °C). Instead of conventional temperature ramp-up process, H2/NH3 gas mixture was introduced during the interruption after the growth of InGaN well layers. The influence of hydrogen flux was investigated. The cross-sectional images of MQW via transmission electron microscope show that a significant atomic rearrangement process happens during the hydrogen treatment. Both sharp interfaces of MQW and homogeneous indium distribution are achieved when a proper proportion of hydrogen was used. Moreover, the luminescence efficiency is improved strongly due to suppressed non-radiative recombination process and a better homogeneity of MQWs. Such kind of atomic rearrangement process is mainly caused by the larger diffusion rate of gallium and indium adatoms in H2/NH3 mixed gas, which leads to a lower potential barrier energy to achieve thermodynamic steady state. However, when excessive hydrogen flux is introduced, the MQW will be partly damaged, and the luminescence performance will deteriorate. [ABSTRACT FROM AUTHOR] more...

The effect of proton irradiation on the electrical properties of AlGaN/GaN high electron mobility transistors (HEMTs) with hydrogen treatment is studied. Hydrogen treatment makes the damage caused by proton irradiation worse. The AlGaN/GaN HEMTs with hydrogen treatment at $2.0 \times 10^{14}\text{p}$ /cm2 3-MeV proton irradiation fluence experience a decrease by 37.3% in the saturation current, a 0.55V positive shift of the threshold voltage (V $_{th}$) and a notable decrease in reverse gate leakage current. While the AlGaN/GaN HEMTs without hydrogen treatment experience a decrease by 18.2% in the saturation current, a 0.211V positive shift of the V $_{th}$. After extracted by the Low Frequency Noise method (LFN method), the flat-band voltage noise power spectral density (S $_{Vfb}$) after hydrogen treatment decreases, and proton irradiation makes the number of defects increased. But the hydrogen treatment causes the S $_{Vfb}$ to rise rapidly after proton irradiation, comparing with the AlGaN/GaN HEMTs without hydrogen treatment. The main mechanism can be attributed to the hydrogen passivation defect and proton irradiation to stimulate the passivation defect to produce composite defects. And the AlGaN/GaN HEMTs with hydrogen treatment is more sensitive to proton irradiation, compared with the AlGaN/GaN HEMTs without hydrogen treatment. [ABSTRACT FROM AUTHOR] more...

Hydrogen treatment is a facile and efficient approach for the enhancement in the functioning of TiO 2 nanoparticles for dye-sensitized solar cells (DSSC). In this work, TiO 2 nanoparticles have been synthesized in the hydrogen environment followed by the deposition onto FTO glass substrates with various film thickness as photoanodes for DSSC. The synthesized hydrogen treated TiO 2 nanoparticles based photoanodes have showed significantly improved photocurrent in the resulting fabricated devices. SEM and TEM analyses have confirmed the particle size and morphology of TiO 2 nanoparticles at various magnifications. The crystalline structure and phase identification were studied by XRD analysis and Raman spectroscopic measurements. The UV–Vis spectroscopy analysis was carried out to find the response of samples for ultraviolet and visible light. The current-voltage measurements have confirmed the improvement of photocurrent that is principally due to improved photo-activity of hydrogen treated TiO 2 nanoparticles. Moreover, hydrogen treated TiO 2 nanoparticles-based photoanode with the film thickness of 11.65 μm has remarkably enhanced power conversion efficiency of 6.05% in DSSCs. The ability of highly photoactive hydrogen treated TiO 2 nanoparticles will provide the new openings in different fields that include photo-electrochemical water splitting and in many other applications. [Display omitted] • Sol-Gel technique was used for the synthesis of H 2 -treated TiO 2 nanoparticles. • Dip coated deposition of H 2 -treated TiO 2 nanoparticles onto FTO substrate. • Various film thicknesses based photoanode of H 2 -treated TiO 2 nanoparticles in DSSC. • Optimized film thickness of 11.65 μm approached PCE of 6.07% in DSSC. [ABSTRACT FROM AUTHOR] more...

The effect of hydrogen on a surface plasmon resonance sensor was studied. The sensor is a glass plate of 1 mm thickness with a gold film applied to one surface. To increase the adhesion of the gold film on the glass a thin chromium interlayer between the gold film and the glass plate was applied. Thickness of the chromium layer was 5 nm. The thickness of the gold film was 50 nm. Hydrogen treatment was performed by means of electrolysis in a 10 % water solution of sulfuric acid (H2SO4). The surface of the gold film served as the cathode. Electrolysis lasted for 6 min. At room temperature due to electrolysis, the gold film was saturated with water. During the hydrogen treatment of the sensor, constant electric currents were maintained. A series of samples were treated with different electrolysis currents (50-2 𝝁A). The influence of the proton flux density to the surface of the gold film on the properties of the surface plasmon resonance sensor was studied. For this purpose, the proton flux density during hydrogen treatment was changed from 8.86.1013 to 3.47.1012 1/(cm².s). Optical properties of treated and untreated sensors were studied experimentally by means of Plasmon-5 spectrometer. Hydrogen treatment changed the optical properties of the surface plasmon resonance sensor over time after hydrogen treatment. The biggest changes occurred during the first days, which gradually slowed down. It was established that after hydrogen treatment the surface plasmon resonance curve was shifted in the direction of larger angles in comparison with the case of an untreated sensor. It was also found that treatment with large fluxes of protons is less effective in changing the optical properties of the sensor than with smaller ones. [ABSTRACT FROM AUTHOR] more...

The present work demonstrates that hydrogen treatment is capable to destroy and to split the surface of silicon single crystal. Hydrogen treatment is performed after the proton irradiation of the silicon surface. All operations with the silicon single crystal are performed at room temperature. The surface of the crystal is irradiated with a proton beam. The proton energy in the beam is 1.5 MeV. The energy spread did not exceed 150 eV. The integral radiation fluence is 2.1014 p/cm². Such a dose of radiation is sufficient to form a thin layer with a high density of radiation defects at a depth of 30 μm under the surface. The existence of this thin layer is confirmed after chemical manifestation by observations on the electron microscope. After irradiation, an electrolytic saturation of the silicon sample with hydrogen is carried out through the irradiated surface. During electrolysis, the irradiated surface of the sample uses as a cathode and the graphite electrode--as an anode. The solution of 10% H2SO4 and 2% KF in water is used for electrolysis. The electrolytic current density is 57.15 mA/cm². After 10 minutes of electrolytic saturation of the sample with hydrogen, part of the sample is split. A portion of the irradiated sample is split along the layer with a high density of radiation defects. [ABSTRACT FROM AUTHOR] more...

Oxygen defects of nanoflower TiO2 photo-catalyst was fabricated at the presence of hydrogen at different temperatures (100–600∘C) and the concentrations of oxygen defects were firstly quantitatively analyzed by hydrogen programmed temperature reduction techniques (H2-TPR). Total oxygen defect concentration and surface oxygen defect concentration were consistent with XPS and EPR results, respectively. Even at the hydrogen thermal temperature of 600∘C, the shape of TiO2 was still kept as nanoflower structure as characterized by SEM. However, the rutile and anatase coexist in the composition of crystal phase when hydrogen reduction temperature of the TiO2 catalyst reached 400∘C to 600∘C as proved by Raman and XRD results. TiO2 sample with oxygen defects shows excellent photo-catalytic activity for degradation of Direct Blue 78(DB) regardless of ultraviolet light (the maximum degradation rate achieved within 100 min was 93.27%) or visible light (the maximum degradation rate achieved within 100 min was 88.25%). The photo-catalytic activity seems to be highly correlated with the surface oxygen defects of TiO2 catalyst. With surface oxygen-defect concentrations increase, the degradation ability on DB was significantly enhanced, while bulk oxygen defects had negligible effect on the photo-catalytic activity. The enhanced photo-catalytic performance of TiO2 with a fixed amount of oxygen defects was attributed to the strong capturing capability of the photo-generated electrons. In addition, the surface defects could also improve the photo-catalytic reaction efficiency. Nanoflower TiO2 has been successfully synthesized by hydrothermal method. Surface defects of the catalyst can be adjusted by precisely controlling the reduction temperature. H2-TPR was used for the first time to quantify oxygen defects at specific concentrations. It is found that the photocatalytic activity increased significantly with the increase of surface oxygen defects concentrations. [ABSTRACT FROM AUTHOR] more...

The fabrication of high purity copper using additive manufacturing has proven difficult because of oxidation of the powder feedstock. Here, we present work on the hydrogen heat treatment of copper powders for electron beam powder bed fusion (EB-PBF), in order to enable the fabrication of high purity copper components for applications such as accelerator components and vacuum electronic devices. Copper powder with varying initial oxygen contents were hydrogen heat-treated and characterized for their chemistry, morphology, and microstructure. Higher initial oxygen content powders were found to not only reduce surface oxides, but also reduce oxides along the grain boundaries and form trapped H2O vapor inside the particles. The trapped H2O vapor was verified by thermogravimetric analysis (TGA) and residual gas analysis (RGA) while melting. The mechanism of the H2O vapor escaping the particles was determined by in-situ SEM heated stage experiments, where the particles were observed to crack along the grain boundaries. To determine the effect of the EB-PBF processing on the H2O vapor, the thermal simulation and the validation of single melt track width wafers were conducted along with melting single layer discs for chemistry analysis. A high speed video of the EB-PBF melting was performed in order to determine the effect of the trapped H2O vapor on the melt pool. Finally, solid samples were fabricated from hydrogen-treated copper powder, where the final oxygen content measured ~50 wt. ppm, with a minimal residue hydrogen content, indicating the complete removal of trapped H2O vapor from the solid parts. [ABSTRACT FROM AUTHOR] more...

Black TiO 2 , which is a promising photocatalyst with enhanced visible light absorption, is a new semiconductor with a smaller band gap than white TiO 2. The synthesis of black TiO 2 has been focused on optimizing hydrogen treatment and exploring different reductants. However, in this work, it was experimentally demonstrated that the phase structure of white TiO 2 precursor plays an important role in its reduction to black TiO 2 by hydrogen treatment, namely, compared with anatase TiO 2 , rutile TiO 2 is much easier to be reduced to black TiO 2. This provides a new direction for synthesis approach of black TiO 2. • It is the first time to experimentally evaluate the phase effect of TiO 2 on its hydrogen reducibility. • Rutile TiO 2 was much easier to be reduced to black than anatase TiO 2. • The reducibility of TiO 2 is strongly dependent on its pristine oxygen defects. • A new direction was provided for synthesis of black TiO 2. [ABSTRACT FROM AUTHOR] more...

Aromatization reaction is of importance in producing aromatics, accompanied by the generation of abundant H2, which may influence the reaction by interacting with the catalyst. In this work, Zn‐containing ZSM‐5 prepared by impregnation was treated in H2 atmosphere at different temperatures, and the evolution in structure, acidity, and Zn species distribution were studied. The catalyst's performance in ethylene aromatization was also evaluated. The results show that the H2 atmosphere enabled the reconstruction of ZnO microparticles and the reformation of Brønsted acid sites on Zn/HZSM‐5 below 200 °C. At an elevated temperature (300 °C), Zn+ species were produced by the reduction of [ZnOZn]2+ as confirmed by in‐situ Zn K‐edge extended X‐ray absorption fine structure (EXAFS) study and density functional theory (DFT) calculation. After H2 pretreatment at 300 °C, the increase in the amount of ZnOH+ species increased the selectivity of Zn‐containing ZSM‐5 for aromatics from 62 % to 67 %. [ABSTRACT FROM AUTHOR] more...

Pure and Ni-doped WO 3 nanoparticles were synthesized by hydraulic acid-assisted precipitation, followed by thermal calcinations. The procedure utilized sodium tungstate (Na 2 WO 4) doped with different amounts of Ni ions. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), and magnetic measurements. The XRD studies demonstrate formation of monoclinic (P21/n) crystal structure for pristine WO 3 at room temperature that gradually transformed into orthorhombic (Pbam) structure by increasing of Ni dopant content. The hydrogenation of the samples did not change their crystalline structure. The optical band gap of the samples was red shifted by Ni doping and blue shifted by hydrogenation. The hydrogenation created ferromagnetic (FM) properties even by small concentrations (∼1%) of Ni dopant. This behavior was discussed within the bound magnetic polarons (BMP) theory. • Simple unique synthesis by hydraulic acid-assisted precipitation method. • 2-Formation of nonstoichiometric WO 2.625 is a direct effect of Ni ionic doping. • 3-Doped Ni ions activate dissociation of adsorbed H 2 molecules during hydrogenation. • 4- Hydrogenation creates RT- FM in Ni-doped tungsten oxide. [ABSTRACT FROM AUTHOR] more...

Abstract SrTiO 3 is a promising material for the photoelectrochemical (PEC) cathodic protection technology due to its intrinsic band structure. Its disadvantage of light absorption only in the ultraviolet region can be effectively solved by Cr doping. The Cr dopant usually exists as two states of Cr3+ and Cr6+, among which the latter one usually behaves as the trapping center for the photoinduced electrons and leads to the decrease of the PEC performance. In this paper, a hydrogen treatment process is performed on the Cr-doped SrTiO 3 to reduce the Cr6+. It is verified that hydrogen treatment reduces Cr6+ to Cr3+, leading to the increase of the concentration of the charge carriers and the decrease of the charge transfer resistance. And also, hydrogen treatment induces the formation of oxygen vacancy, which leads to the negative shift of conduction band potential and the increase of the concentration of the charge carriers. The effect of the hydrogen treatment temperature is further studied in this work. Higher temperature will promote the reduction degree of Cr6+ and increase the concentration of oxygen vacancy. However, hydrogen treatment with excessively high temperature will induce too high concentration of oxygen vacancy, which would act as the recombination centers of the photogenerated charge carriers, suppress the mobility conduction and thus lead to the decrease of the PEC performance. Therefore, benefiting from the Cr6+ reduction and modification with appropriate concentration of oxygen vacancy, the Cr-doped SrTiO 3 with hydrogen treatment at 250 °C shows the optimal PEC cathodic protection performance in NaCl solution. Highlights • H 2 treatment was performed on the Cr-doped SrTiO 3. • H 2 treatment reduces the Cr6+ and induces the formation of oxygen vacancy. • Photoelectrochemical cathodic protection performance is significantly increased after H 2 treatment. • Appropriate H 2 treatment temperature is necessary for the enhanced performance. [ABSTRACT FROM AUTHOR] more...

Plate of p-silicon of 0.35 mm thickness was the sample of present studies. Two gold film contacts of 50 nm thickness were deposited on the opposite surfaces of p-silicon sample. For the manufacturing of gold film contacts the method of direct contact heating in a tungsten boat was used. The surface of the silicon plate was activated before the deposition of gold by dipping the samples into a 0.5 % solution of hydrofluoric acid. The silicon wafer was then washed with distilled water, dried and placed in a container for substrates. After deposition of the gold film contact, the plate of p-silicon was cut in several samples. The hydrogen treatment of only one gold film contact was executed by means of electrolysis in 10 % water solution of H2SO4. The gold contact was the cathode and the graphite electrode was the anode. The second gold film contact was isolated during the electrolysis. The electrolysis lasted for 6 min. The current density during electrolysis was 117.5 A/m2. The p-silicon samples with gold contacts processed by hydrogen were stored at room conditions. The time dependence of the volt-ampere characteristics of the samples was investigated. The resistance of the gold film contact increased in the first few hours after hydrogen processing. But then, during the week after hydrogen treatment, the resistance of the gold film contact constantly diminished. During the next week, the resistance of the gold film contact did not change. The hydrogen saturation of the gold film contact caused the significant reduction of the resistance of the gold contact. After treatment and exposure at room conditions, the final resistance of the gold film contact decreased by almost 1.5 times in comparison with the contact resistance before hydrogen treatment. [ABSTRACT FROM AUTHOR] more...

An increase of integrated photoluminescence (PL) intensity has been observed in a GaN-based multiple quantum wells (MQWs) sample. The integrated intensity of TDPL spectra forms an anomalous variation: it decreases from 30 to 100 K, then increases abnormally from 100 to 140 K and decreases again when temperature is beyond 140 K. The increased intensity is attributed to the electrons and holes whose distribution are spatial non-equilibrium distributed participated in the radiative recombination process and the quantum barrier layers are demonstrated to be the source of non-equilibrium distributed carriers. The temperature dependence of this kind of spatial non-equilibrium carriers’ dynamics is very different from that of equilibrium carriers, resulting in the increased emission efficiency which only occurs from 100 to 140 K. Moreover, the luminescence efficiency of MQWs with non-equilibrium carriers is much higher than that without non-equilibrium carriers, indicating the high luminescence efficiency of GaN-based LEDs may be caused by the non-equilibrium distributed carriers. Furthermore, a comparison analysis of MQWs sample with and without hydrogen treatment further demonstrates that the better quantum well is one of the key factors of this anomalous phenomenon. more...

Cadmium oxide powder doped with Tb ions was synthesised by thermal decomposition of cadmium Hydroxychloride Cd(OH)Cl. The molar content of Tb is 2.6%. The purpose of the present study is to tailoring room-temperature ferromagnetic (RT-FM) properties to CdO in order to use it in the field of dilute magnetic semiconductors (DMS). The samples characterised by X-ray fluorescence (XRF) and X-ray diffraction (XRD). The optical band gap of the prepared powders was determined by diffuse reflection spectroscopy (DRS). Terbium ions doped in CdO are employed as source of FM properties. The electronic medium of Spin-Spin interaction in host CdO is studied by annealing in hydrogen atmosphere. Magnetic measurements reveal that Tb-doped CdO powder behaves as paramagnet defeating the intrinsic diamagnetic behaviour of CdO. However, after annealing in hydrogen atmosphere, RT-FM properties were created. Thus, it was proved that magnetic properties could be tailored by doping and post treatment under H2 atmosphere. more...

Improving the separation efficiency of photogenerated electron–hole pairs and the conductivity of electrons to photoanode substrates are critical to achieve high‐performance photoelectrochemical (PEC) water splitting. Here, a SnS2/H‐TiO2/Ti heterojunction photoanode was fabricated with SnS2 nanosheets vertically grown on hydrogen‐treated TiO2 (H‐TiO2) nanotube arrays on a Ti substrate. It showed a significantly enhanced photocurrent of 4.0 mA cm−2 at 1.4 V (vs. reversible hydrogen electrode) under AM 1.5 G illumination, 70 times higher than that of SnS2/TiO2/Ti. Kelvin probe force microscopy measurements indicated that photogenerated electrons could be easily transported through the SnS2/H‐TiO2 interface but not through the SnS2/TiO2 interface. Through hydrogen treatment, defects were created in H‐TiO2 nanotubes to convert type I junctions to type II with SnS2 nanosheets. As a result, a high efficiency of electron–hole separation at the SnS2/H‐TiO2 interface and a high electron conductivity in H‐TiO2 nanotubes were achieved and improved PEC performance. These findings show an effective route towards high‐performance photoelectrodes for water splitting. Exactly your type: A type II heterojunctioned photoanode based on SnS2 nanosheets/hydrogenated TiO2 nanotube arrays (SnS2/H‐TiO2/Ti) shows a significantly enhanced photocurrent of 4.0 mA cm−2 at 1.4 V (vs. RHE), 70 times higher than a type I heterojunctioned photoanode of SnS2 nanosheets/TiO2 nanotube arrays (SnS2/TiO2/Ti). Hydrogenation creates defects in TiO2 nanotubes, improves their electrical conductivity and converts their junctions with SnS2 nanosheets from type I to type II. [ABSTRACT FROM AUTHOR] more...

Europium oxychloride nanopowders codoped with copper/nickel ions were synthesized by solvothermal route followed by a subsequent heat treatment. The present study focuses on determination the conditions required to create stable ferromagnetic (RT-FM) properties in EuOCl crystalline powder. For that purpose, nickel (Ni2+) ions were used as dopant. It was found that such doping could not create FM properties in EuOCl unless followed by hydrogenation. The presence of transition metal (TM) Cu2+ as impurity dopant ions assists to dissociate H2 molecules into H atoms. Moreover, dopant Cu2+ ions donate polarons (electrons) that develop the electronic medium (EMI) of the spin-spin (S.S) long-range interaction in the EuOCl crystalline lattice. Systematic structural, optical, and magnetic properties of pure and Cu/Ni-codoped EuOCl samples were investigated. Their variations with post-annealing treatment in different conditions (temperature and atmosphere) were also studied. The optical properties were studied by diffuse reflection spectroscopy (DRS) method. The magnetic measurements reveal that hydrogenated Cu/Ni-codoped EuOCl nanopowders have RT-FM properties with saturation magnetisation ~ 1.7 emu/g. The physical explanations and discussions were given in the framework of bound magnetic polarons (BMP) theory. Thus, EuOCl nanocrystalline powder could be used as a potential candidate for optical applications with tailored magnetic properties. [ABSTRACT FROM AUTHOR] more...

Graphical abstract Highlights • Dual modification, hydrogen treatment and FeOOH loading in rf-sputtered bismuth vanadate (BiVO 4) thin films. • Hydrogen treatment in BiVO 4 improves the bulk charge transport. • FeOOH in BiVO4 act as OEC and improve the charge transport at the semiconductor/electrolyte interface. • The resulting FeOOH/H:BiVO 4 photoanode achieves a considerably higher photocurrent density (J p ∼2.16 mA cm–2 at 1.23 V RHE). • Dual modification strategy offers a simple but effective approach to improving the water oxidation performance of BiVO 4. Abstract The water oxidation capability of the promising photoanode bismuth vanadate (BiVO 4) is hampered by poor bulk electron transport and by high rates of charge recombination at the semiconductor/electrolyte interface. Here, we demonstrate that a dual modification of BiVO 4 by: (i) annealing in a hydrogen-containing environment and (ii) coating with FeOOH overlayer substantially enhances the water oxidation ability of BiVO 4 photoanodes. Hydrogen treated, FeOOH coated BiVO 4 photoanodes exhibit a water oxidation photocurrent density of 2.16 mA cm−2 at 1.23 V RHE , which is 5 times higher than for untreated BiVO 4 films. Moreover, they showed an impressive low photocurrent onset potential of −0.11 V RHE. A stable photocurrent was observed for 1 h of water oxidation measurement at 1.23 V RHE under 1 Sun illumination. The enhanced photocurrent of FeOOH/H:BiVO 4 photoanode is ascribed to an improved bulk charge transport, as confirmed by impedance spectroscopy measurements and Mott-Schottky analysis. The cathodic shift of the onset potential originates from a lowering of the flat band potential and from an improvement of the charge transport at the semiconductor/electrolyte interface. The dual modification strategy used here offers a simple but effective approach of improving the water oxidation performance of BiVO 4. [ABSTRACT FROM AUTHOR] more...

The effect of hydrogen treatment on the phase composition and structure of the Laves phases in the Zr (Hf)–Ni–Al systems has been studied. It is found that grinding in a planetary-ball mill leads to partial glass formation in the alloys, the Laves phases have nanocrystallites ≈ 6–14 nm in size, and a phase transition takes place in the HfAl1.4Ni0.6 alloy. The nanocrystallites of the Laves phases refine with increasing grinding time. It is shown that interaction of the as-cast alloys with hydrogen at 3.0 MPa and 950°C finishes with their homogenization and formation of additional phases, such as Zr2Al3 and Zr6Ni8Al15, for the zirconium alloys. Besides the starting phase of MgCu2 structural type, a phase with MgZn2 structure appears in the hafnium alloys. The ball-milled zirconium alloys partially oxidize after the heat treatment in hydrogen. [ABSTRACT FROM AUTHOR] more...

Abstract Tungsten oxide (WO3) nanoparticles doped with different amounts of manganese ions (W1−xMnxO3, where x = 0.011, 0.022 and 0.044) were synthesised by hydraulic acid-assisted precipitation, followed by thermal calcinations. The powders were characterised by X-ray fluorescence (XRF), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS) and magnetic measurements. The monoclinic structure at room temperature (∼293 K) found for un-doped WO3 was preserved even with Mn doping. However, doping with Mn ions caused decease in unit-cell volume and slight increase in crystallite size (CS) of host WO3. The hydrogenation was observed to corrode the crystallites without changing in crystalline structure. Controllable room-temperature ferromagnetic (RT-FM) properties were obviously observed with hydrogenated WO3 doped with Mn. In addition, there existed an optimum doping concentration of Mn in WO3 to obtain superior FM properties. Therefore, Mn-doped WO3 nanopowders, owning to these amazingly tunable magnetic properties, could be considered a potential candidate for many applications partially required FM properties such as optical phosphors and catalysts. [ABSTRACT FROM AUTHOR] more...

The fabrication of high purity copper using additive manufacturing has proven difficult because of oxidation of the powder feedstock. Here, we present work on the hydrogen heat treatment of copper powders for electron beam powder bed fusion (EB-PBF), in order to enable the fabrication of high purity copper components for applications such as accelerator components and vacuum electronic devices. Copper powder with varying initial oxygen contents were hydrogen heat-treated and characterized for their chemistry, morphology, and microstructure. Higher initial oxygen content powders were found to not only reduce surface oxides, but also reduce oxides along the grain boundaries and form trapped H2O vapor inside the particles. The trapped H2O vapor was verified by thermogravimetric analysis (TGA) and residual gas analysis (RGA) while melting. The mechanism of the H2O vapor escaping the particles was determined by in-situ SEM heated stage experiments, where the particles were observed to crack along the grain boundaries. To determine the effect of the EB-PBF processing on the H2O vapor, the thermal simulation and the validation of single melt track width wafers were conducted along with melting single layer discs for chemistry analysis. A high speed video of the EB-PBF melting was performed in order to determine the effect of the trapped H2O vapor on the melt pool. Finally, solid samples were fabricated from hydrogen-treated copper powder, where the final oxygen content measured ~50 wt. ppm, with a minimal residue hydrogen content, indicating the complete removal of trapped H2O vapor from the solid parts. more...

Abstract: Atomically thin black phosphorus (BP) exhibits great potential for wide applications in future electronic and optoelectronic devices. However, BP exhibits fast ambient degradation and is thus severely limited in practical applications. Here, a simple strategy using hydrogen treatment to enhance the environmental stability of BP flakes is reported. Owing to the drastically suppressed ambient degradation by hydrogen treatment, atomic BP flakes are just slightly corroded on the surface even after up to 4 weeks in air, and more impressively, the BP field‐effect transistors still maintain over 85% of their initial mobility and ION/IOFF ratio. First‐principle calculations indicate that the hydrogen molecules are probably embedded between BP layers, and shift down the conduction band minimum, which strongly protects against the formation of superoxide on the surface and thus suppresses the ambient degradation of BP. This study provides a simple and nondestructive route to achieve air‐stable BP devices. [ABSTRACT FROM AUTHOR] more...

The synergistic mechanism of hydrogen treatment technology and heterogeneous structure was firstly reported to enhance the photoelectrochemical properties of SrTiO 3 /TiO 2 composite. The SrTiO 3 nanoparticles were successfully synthesized on the surface of TiO 2 nanotube arrays to form SrTiO 3 /TiO 2 heterostructure by a hydrothermal method. The heterogeneous structure was further optimized by hydrogen treatment under calcinations to prepare the hydrogen-treated SrTiO 3 /TiO 2 nanotube arrays heterojunction composite (H-SrTiO 3 /TiO 2 ). The photoelectrochemical performance of H-SrTiO 3 /TiO 2 was significantly enhanced, whose photocurrent density was 3 times of that of hydrogen treated TiO 2 (H-TiO 2 ) and 1.5 times of that of SrTiO 3 /TiO 2 heterostructures. The improved photoelectrochemical performance of H-SrTiO 3 /TiO 2 can be attributed to the synergistic effect of hydrogen treatment and heterojunction, which results in the enhancement of light absorption and the increase of photogenerated carrier concentration. [ABSTRACT FROM AUTHOR] more...

Widespread application of solar water splitting for energy conversion is largely dependent on the progress in developing not only efficient but also cheap and scalable photoelectrodes. Metal oxides, which can be deposited with scalable techniques and are relatively cheap, are particularly interesting, but high efficiency is still hindered by the poor carrier transport properties (i.e., carrier mobility and lifetime). Here, a mild hydrogen treatment is introduced to bismuth vanadate (BiVO4), which is one of the most promising metal oxide photoelectrodes, as a method to overcome the carrier transport limitations. Time-resolved microwave and terahertz conductivity measurements reveal more than twofold enhancement of the carrier lifetime for the hydrogen-treated BiVO4, without significantly affecting the carrier mobility. This is in contrast to the case of tungsten-doped BiVO4, although hydrogen is also a donor type dopant in BiVO4. The enhancement in carrier lifetime is found to be caused by significant reduction of trap-assisted recombination, either via passivation or reduction of deep trap states related to vanadium antisite on bismuth or vanadium interstitials according to density functional theory calculations. Overall, these findings provide further insights on the interplay between defect modulation and carrier transport in metal oxides, which benefit the development of low-cost, highly-efficient solar energy conversion devices. [ABSTRACT FROM AUTHOR] more...

In this paper, we present an investigation on two types of nanodiamond (ND) powders with average size of particles around 250 nm and having different sp 2 (graphite phase) and sp 3 (diamond phase) carbon contents. The ND surface modification is carried out by physical methods i.e. treatments in H 2 microwave plasma. The quantum efficiency (QE) of photocathodes and the stability of aqueous dispersions are assessed by photoemission and zeta potential (ZP) measurements, respectively. The resultant hydrogenated surface affects in the solid state the QE of ND-based photocathodes and in solution the particle ZP. The effect of the hydrogen treatment is beneficial inducing an enhancement of photocathode QE and a corresponding increase of the ZP. A schematized energy diagram is proposed to illustrate and explain the strong correlation between QE and ZP parameters. [ABSTRACT FROM AUTHOR] more...

Hierarchical titanium oxide nanostructures were synthesized by Pulsed Laser Deposition (PLD) and investigated as photoanodes for photoelectrochemical water splitting. An explorative combined approach to enhance TiO 2 performance was based, on the one hand, on the employment of hydrogenation treatments with the aim of improving quantum efficiency and extending light absorption to the visible range; on the other hand, on the optimization of morphology and structure, to increase light harvesting and charge separation/transport. This approach was pursued by depositing at a fixed background pressure with variable oxygen content (to control the growth morphology and structure) and by annealing in a Ar/H 2 mixture (in substitution of or in combination with air annealing), in order to induce crystallization to the anatase structure and reduction/hydrogenation of the material. Morphology, structure and optical properties were investigated by SEM, Raman spectroscopy, X-ray diffraction and UV–visible-IR spectroscopy. An optical absorption tail towards the visible range appeared after Ar/H 2 annealing, without any significant modification of the nanoscale structure after the different thermal treatments. Photocurrent measurements under solar simulator illumination showed a noteworthy increase of photoresponse for Ar/O 2 -deposited samples with air annealing followed by Ar/H 2 annealing. These findings can be ascribed to the combination between an improved charge transport of TiO 2 deposited in low-O 2 atmosphere and a hydrogenation effect on the nanostructures surface layers, leading to improved quantum efficiency. [ABSTRACT FROM AUTHOR] more...

To enhance the quality of InGaN/GaN multiple quantum wells (MQWs), a small hydrogen flow is introduced to treat the upper well/barrier interface. High-resolution X-ray diffraction results indicate that hydrogen treatment improves the interface quality of MQWs. Room temperature photoluminescence (PL) tests show that integrated PL intensity is enhanced by 57.6% and line width is narrowed, while emission peak energy is almost unchanged. On the basis of temperature-dependent PL characteristics analysis, it is concluded that hydrogen treatment decreases non-radiative recombination centers in active region, yet has little impact on carrier localization. Moreover, surface roughness and V-pit density are significantly reduced after hydrogen treatment as revealed by atomic force microscopy. Because the emission energy is quite stable after the hydrogen treatment, this method can also be promoted to improve the quality of green and yellow-green emission MQWs. [ABSTRACT FROM AUTHOR] more...

The aim of this study was to investigate the influence of doping and hydrogenation on the structural, optical and magnetic properties of dia-magnet Lanthanum oxychloride (LaOCl). LaOCl codoped with palladium and cobalt samples were successfully synthesized by solvothermal route, followed by a subsequent heat treatment process (annealing) at 600, 750 and 900 °C. Furthermore, annealing in hydrogen gas (hydrogenation) was carried out to the samples at 400 °C. The crystallite size (CS) of the samples were found to be influenced by annealing and hydrogenation processes as it ranged from 10.6 to 38 nm, as confirmed by X-ray diffraction (XRD) technique. Results also revealed dramatic changes in magnetic properties of the synthesized samples treated with annealing and hydrogenation. Vibrating sample magnetometer (VSM) analysis showed that Pd/Co-codoped LaOCl nanopowders own room temperature ferromagnetic (RT-FM) properties when post-annealed in air at 750 °C. It is also confirmed that created saturation magnetization is strongly affected by hydrogenation as it raised by ~ 50 time, (8.6 memu/g before and 410 memu/g after hydrogenation). The physical explanations and discussions were given in the framework of bound magnetic polarons (BMP) theory explaining how magnetic properties can be tailored from diamagnetic (DM) in pure LaOCl compound to FM under doping and hydrogenation. [ABSTRACT FROM AUTHOR] more...

Terbium oxychloride (TbOCl) nanopowders in pure state and codoped with Cu/Fe dopants were synthesised by a solvothermal route followed by a subsequent heat treatment process. Their structural and optical properties were studied as a function of post-annealing treatment conditions (temperature and atmosphere). The optical properties were studied by the diffuse reflection spectroscopy (DRS) method. Actually, the present work focused on the possible creation of stable room-temperature ferromagnetic (RT-FM) properties within TbOCl. Therefore, dopant impurity iron (Fe) ions were used as stable sources of FM properties. However, low doping concentration of Fe could not be able to create FM properties unless followed by annealing in hydrogen-gas atmosphere (hydrogenation). The transition metal (TM) dopant ions (Fe and Cu) could play a role of catalyst in order to dissociate H molecules into H atoms during a hydrogenation process. Moreover, dopant Cu ions were also used as donors of polarons to the oxygen vacancies in order to enhance the electronic medium (electromagnetic interference) for spin-spin (SS) long-range interaction. The magnetic measurements reveal that hydrogenated Cu/Fe-codoped TbOCl nanopowders have RT-FM properties with saturation magnetisation of ∼2.2 emu/g. Thus, TbOCl nanocrystals could be used as a potential candidate for optical applications with tailored magnetic properties. [ABSTRACT FROM AUTHOR] more...

[Display omitted] • Excess hydroxyl groups were created by hydrogen treatment. • OH B injected electrons into TiO 2 surface and altered electron distribution. • OH B created a hole transfer channel to toluene. • OH B built an electron transfer channel to O 2. • OH B induced a synergistic effect of O 2 , H 2 O, and toluene on charge separation. The mechanism of charge transfer to reactants during photocatalytic degradation of volatile organic compounds remains unclear. Herein, TiO 2 was heated in a hydrogen atmosphere to increase the content of bridging hydroxyl (OH B), and atmosphere surface photovoltage spectroscopy (ASPV) was used to study the effect of changed surface sites on the transfer of photogenerated charge carriers to reactants (O 2 , H 2 O, and toluene). Results showed that the removal rate and mineralization efficiency of toluene were improved after hydrogen treatment. The ASPV tests found that hydrogen treatment created electron transfer channels to O 2 and hole transfer channels to toluene/water, and reduced H 2 O's interference with electron utilization by O 2. Hydrogen in the newly formed OH B changed the electron distribution on the TiO 2 surface by injecting electrons. The OH B and surrounding Ti4−x ions altered the adsorption form of H 2 O, thereby facilitating the transfer of electrons to O 2 and holes to toluene. [ABSTRACT FROM AUTHOR] more...

Graphene grown on C-face SiC substrates using two procedures, high and low growth temperature and different ambients, was investigated using Low Energy Electron Microscopy (LEEM), X-ray Photo Electron Electron Microscopy (XPEEM), selected area Low Energy Electron Diffraction (μ-LEED) and selected area Photo Electron Spectroscopy (μ-PES). Both types of samples showed formation of μm-sized grains of graphene. The sharp (1 × 1) μ-LEED pattern and six Dirac cones observed in constant energy photoelectron angular distribution patterns from a grain showed that adjacent layers are not rotated relative to each other, but that adjacent grains in general have different azimuthal orientations. Diffraction spots from the SiC substrate appeared in μ-LEED patterns collected at higher energies, showing that the rotation angle between graphene and SiC varied. C 1s spectra collected did not show any hint of a carbon interface layer. A hydrogen treatment applied was found to have a detrimental effect on the graphene quality for both types of samples, since the graphene domain/grain size was drastically reduced. From hydrogen treated samples, μ-LEED showed at first a clear (1 × 1) pattern, but within minutes, a pattern containing strong superstructure spots, indicating the presence of twisted graphene layers. The LEED electron beam was found to induce local desorption of hydrogen. Heating a hydrogenated C-face graphene sample did not restore the quality of the original as-grown sample. more...