Effect Of H3BO3 Research Articles

Boric Acid‐Assisted Pyrolysis for High‐Loading Single‐Atom Catalysts to Boost Oxygen Reduction Reaction in Zn‐Air Batteries

The emerging of single‐atom catalysts (SACs) offers a great opportunity for the development of advanced energy storage and conversion devices due to their excellent activity and durability, but the actual mass production of high‐loading SACs is still challenging. Herein, a facile and green boron acid (H3BO3)‐assisted pyrolysis strategy is put forward to synthesize SACs by only using chitosan, cobalt salt and H3BO3 as precursor, and the effect of H3BO3 is deeply investigated. The results show that molten boron oxide derived from H3BO3 as ideal high‐temperature carbonization media and blocking media play important role in the synthesis process. As a result, the acquired Co/N/B tri‐doped porous carbon framework (Co–N–B–C) not only presents hierarchical porous structure, large specific surface area and abundant carbon edges but also possesses high‐loading single Co atom (4.2 wt.%), thus giving rise to outstanding oxygen catalytic performance. When employed as a catalyst for air cathode in Zn‐air batteries, the resultant Co–N–B–C catalyst shows remarkable power density and long‐term stability. Clearly, our work gains deep insight into the role of H3BO3 and provides a new avenue to synthesis of high‐performance SACs.

Thermodynamic and application study of complicated extraction system Ce(IV)–HF–H3BO3–H2SO4 using Cyanex 923

This article aims to reduce the environmental pollution while maximizing the recovery of REEs as well as associate resource-fluorine (F) from bastnaesite. This paper investigates the extraction equilibrium process and mechanism of Ce(IV)–HF–H3BO3–H2SO4 system using Cyanex 923. Extraction equilibrium process of different systems, including HF–H2SO4, H3BO3–HF–H2SO4, and Ce(IV)–HF–H2SO4, were studied in detail and the corresponding extraction mechanisms were also determined. It is noteworthy that a synergistic effect between B–F and an antagonistic effect between Ce(IV)–F were discovered first in the extraction process by Cyanex 923. Besides, H3BO3 is found to be able to promote the extraction of F in quantitation by Cyanex 923. FTIR and 11B and 19F NMR were adopted to characterize the different loaded organic phase. Based on these results, the extraction mechanism of complicated system Ce(IV)-HF-H3BO3–H2SO4 was further determined. Besides, the effect of H3BO3 on the extraction and stripping of Ce(IV) in complicated system was studied. Moreover, it shows that the addition of H3BO3 has nothing to do with the purity of obtained CeF3 particle from bastneasite liquor in the practical system. Adding H3BO3 into bastnaesite leach liquor, on the one hand, will be beneficial for the recovery yield of Ce and F. On the other hand, it can avoid from environmental pollution caused by emission of F-containing waste water as well as reducing the waste residue.

Pyrolysis and Combustion Behavior of Pinewood After the Addition of Flame Retardants

Abstract To investigate the effects of flame retardants on pinewood combustion, a comprehensive analytical method has been devised based on a full description of the pyrolysis process. With the addition of ammonium polyphosphate (APP), ammonium dihydrogen phosphate (NH4H2PO4), and boric acid (H3BO3), the total amount of cellulose/hemicellulose decomposition products increased by 27.9, 63.1, and 14.2 %, respectively, and the yield of lignin-derived products decreased by 22.8, 57.7, and 13.2 %, respectively. Because of the easiest release of phosphoric acid, NH4H2PO4 had the most obvious impact on destruction of the char structure by volatiles released in the pyrolysis process, resulting in the highest peak heat release rate of 273.46 kW/m2 at a heat flux of 50 kW/m2. The addition of APP induced similar changes in the pyrolysis products, but it showed the best fire-resistance properties because of its lower surface temperature and less destruction of the char layer by volatiles. The effect of H3BO3 was weakest.

Effect of H3BO3 on phases, micromorphology and persistent luminescence properties of SrAl2O4: Eu2+, Dy3+ phosphors

Long afterglow material SrAl2O4: Eu2+, Dy3+ were synthesized by solution combustion method, and the effects of the concentration of H3BO3 on phases, micromorphology, photoluminescence properties, long afterglow properties and thermoluminescence glow curves of the phosphors were studied systematically. Phosphor with SrAl2O4 pure phase can be obtained when the concentration of H3BO3 is 2 mol%. The micromorphology of the phosphors changed a lot due to the varied amount of H3BO3, and nanoflower like phosphors was formed when the concentration of H3BO3 is 10 mol%. With the continue increasing of H3BO3, the nanoflower aggregate together to form irregular particles with a larger size and the petal gradually disappear while the luminescence intensity shows a linear increase. The decay curves and the Thermoluminescence glow curves were also measured, and the depth of traps were calculated. The results show that with the increasing concentration of H3BO3, the trap depth increasing gradually. However, the trap depth decrease gradually when the content of H3BO3 beyond 20 mol%, which caused by the diffusion of surplus B3+ in the interstitial sites.

Effect of H3BO3on the Corrosion Properties of Ni-B Based Electroplating Coatings

Effect of H₃BO₃on the Corrosion Properties of Ni-B Based Electroplating Coatings

Effect of H3BO3 on sintering behavior and microwave dielectric properties of monoclinal structure ZnZrNb2O8 ceramics

The effects of H3BO3 additions on sintering characteristic, phase composition, microstructure and microwave dielectric properties of ZnZrNb2O8 ceramics were investigated. The ZnZrNb2O8 ceramics were prepared by the solid-state method. The phase composition, microstructure and elemental composition of the ceramics were studied using X-ray diffraction, scanning electron microscopy and energy dispersive analysis. Only a single-phase ZnZrNb2O8 was formed in ZnZrNb2O8 ceramics with H3BO3 addition. A small amount of H3BO3 successfully reduced the sintering temperature of ZnZrNb2O8 ceramics to 1200 °C without much degradation of the microwave dielectric properties. In addition, the τf values were shifted to positive direction with the H3BO3 addition. Typically, the 1 wt% H3BO3 added ZnZrNb2O8 ceramics sintered at 1200 °C for 4 h exhibited excellent microwave dielectric properties with er = 27.04, Q·f = 64,980 GHz and τf = −34.3 ppm/ °C.

Effect of H3BO3 on corrosion in 0.01 M NaCl solution of the interface between low alloy steel A508 and alloy 52 M

The corrosion of the low alloy steel A508-alloy 52M interface region in buffered and non-buffered chloride containing solutions was studied by using the scanning vibrating electrode technique (SVET), scanning ion-selective electrode technique (SIET), and time of flight secondary ion mass spectroscopy (ToF-SIMS). The typical pit in low alloy steel A508 formed in NaCl solution was stopped immediately when H3BO3 was added to the NaCl solution, and the pit became cathodic. With increasing immersion time, H3BO3 entered into the pit, and the corrosion of A508 became general corrosion.

Effect of H3BO3 on the persistent luminescence and photocatalytic properties of ZnGa2O4 phosphors

The phosphor ZnGa2O4 was synthesized via H3BO3 assisted solid-state reaction method. The effect of H3BO3 on the crystal structure, photoluminescence, persistent luminescence, and photocatalytic properties of the phosphor was studied in detail. X-ray diffraction patterns indicated that a pure phase ZnGa2O4 could be achieved at the sintered temperature 1200°C adding H3BO3 of 10mol%. The samples exhibited a wide emission band peak at 423nm and a narrow emission peak at 502nm under ultraviolet excitation (254nm). Moreover, H3BO3 improved the persistent luminescence properties of ZnGa2O4 phosphor effectively because H3BO3 increased the electron traps and improved the depth of the traps. In addition, photocatalytic activity test shown that ZnGa2O4 phosphor with H3BO3 exhibited lower catalytic activities than the pure ZnGa2O4 for the degradation of Rhodamine B by the ultraviolet irradiation. The reason was that the particle size of the ZnGa2O4 phosphor became larger when the ZnGa2O4 was synthesized using H3BO3 as flux.

Hydrogen Production from Sodium Borohydride in Boric Acid-water Mixtures

Borohydride, which reacts slowly with water, is developed as hydrogen production and storage options. The reaction is significantly accelerated by the rise of temperature or by the addition of acidic substances. Boric acid (H3BO3) can be used as an alternative to water for the hydrogen production in the hydrolysis of sodium borohydride (NaBH4). The effect of H3BO3 and NaBH4–H3BO3 molar ratios was studied at 30, 40, 50, 60, and 80°C on the hydrogen production of NaBH4. All of these results show that H3BO3 is a relatively green acid compound for hydrogen generation from NaBH4 and the H3BO3-water-NaBH4 system being quite simple for single-use applications. It was found that the reaction between H3BO3 and NaBH4 complied with a second order kinetics rate with 0.5 reaction orders versus NaBH4 concentration and 1.5 orders versus H3BO3 concentration, and the activation energy for conversion was calculated as 18.01 kJ mol−1.

Effect of H3BO3 on structure and long persistence properties of Y1.98O3：Eu, Dy red long-afterglow phosphor

The phosphor Y1.98O3: Eu0.013+, Dy0.013+ was prepared by high temperature solid reaction method. X-ray powder diffraction (XRD), scanning electronic microscope (SEM), photoluminescence spectra (PL), and single-photon counter system were used to investigate the structure, morphology, luminescent properties, and decay characteristics of the phosphor Y1.98O3: Eu0.013+, Dy0.013+ which was synthesized with different contents of H3BO3. Results show that the structure of the H3BO3-contained phosphors can keep Y2O3 matrix when the content of H3BO3 is below 8%(mol), and the particles size of phosphors increases during the addition of H3BO3. The luminescence of phosphors come from the transition of 5D0→7FJ of Eu3+, the main emission peaks at 612 nm and the intensity is increased linearly with the increase of H3BO3 content. Phosphors show better afterglow characteristics during the increase of H3BO3.The measurement of thermoluminescence(TL) reveals that the addition of H3BO3 increases the trap depth and trap concentration in the host, hence the afterglow characteristics become better.

Effect of H3BO3 on the phase stability and long persistence properties of Sr3.96Al14O25:Eu2+0.01, Dy3+0.02 phosphor

Sr3.96Al14O25:Eu2+,Dy3+ long persistent materials with different weights of H3BO3 prepared by the high temperature solid-state reaction method were characterized by X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), photoluminescence spectra (PL), and thermoluminescence (TL). The results of XRD indicate that the 3% addition of H3BO3 favorable for the formation of pure phase Sr4Al14O25, and SrAl12O19 was generated when there is a low content or high content of H3BO3. The average grain sizes of samples grow bigger with an increase of H3BO3. PL spectra show that the emission peak does not shift evidently and the emission intensity changes little, indicating that the different amount of H3BO3 has little influence on the crystal field. The decay characteristics and TL measurement show that H3BO3 affects the afterglow properties of Sr3.96Al14O25:Eu2+,Dy3+, because the increasing H3BO3 leads to more defects in the Sr4Al14O25 matrix.

Ba3Tb(BO3)3 ∶Ce3+ : a green emitting phosphor for white LED

Two green emitting phosphors, Ba3Tb(BO3)3 and Ba3Tb(BO3)3 ∶Ce3+, are synthesized by the high temperature solid-state method, and their luminescent characteristics are investigated. Ba3Tb(BO3)3 phosphor shows several emission peaks located at 439, 493, 547, 589 and 629 nm separately. The emission peaks correspond to the 5D3→7F4 and 5D4→7FJ=6. 5, 4, 3 transitions of Tb3+, respectively, and the maximal peak is 547 nm. For the 547 nm emission, the excitation spectrum consists of several bands, and the maximal peak is located at 380 nm. The Ce3+-activated Ba3Tb(BO3)3 phosphor is studied, and the result shows that the emission spectrum distribution of Ba3Tb(BO3)3 ∶Ce3+ is the same as that of Ba3Tb(BO3)3 phosphor, however, its emission intensity is higher than that of Ba3Tb(BO3)3,which is attributed to the sensitizing action of Ce3+ on Tb3+ in Ba3Tb(BO3)3. For the 547 nm emission, the excitation spectrum of Ba3Tb(BO3)3 ∶Ce3+presents a broad band, differing from that of Ba3Tb(BO3)3 phosphor. The effect of H3BO3 on the emission intensity of Ba3Tb(BO3)3 ∶Ce3+ phosphor is investigated, and the results show that the emission intensity can reach a maximum for 15 wt% excessive H3BO3. All the results show that Ba3Tb(BO3)3 ∶Ce3+ is a green emitting phosphor for white LED.

Effect of H3BO3 on preparation and luminescence properties of submicron green-emitting Ca3Sc2Si3O12 ∶Ce phosphor

Green-emitting Ca3Sc2Si3O12:Ce3+ phosphors for white LED are successfully synthesized by a gel-combustion method. The as-synthesized phosphors are investigated by XRD, SEM, and fluorescence spectrophotometer. The results indicate that the crystal structure of the phosphor is pure. The particle morphology of the sample is basically spherical in shape. The particle size is smaller than 1μm. The emission spectrum shows a broad band emission, and the main emission peak locates at 505 nm. Bright green-emission broadening is attributed to the characteristic emissions 5d-2F5/2 and 5d-2F7/2 transitions of Ce3+. The optimal doping concentration of Ce in Ca3-xSc2Si3O12:Ce is x=0.1. The thermal stability and the luminescence intensity of the Ca3Sc2Si3O12:Ce3+ are significantly improved compare with those of YAG:Ce.

Effect of H3BO3 on composition and luminescence properties of BaAl2Si2O8：Eu2+ blue phosphor

The Eu2+ activated blue emitting BaAl2Si2O8：Eu2+ phosphor was synthesized by one-step calcination process of precursor prepared with chemical coprecipitation. X-ray diffraction （XRD），fluorescence spectrophotometry and scanning electron microscopy were used to investigate the structure，luminescent property and morphology of the BaAl2Si2O8：Eu2+ blue phosphor. The results showed that BaAl2Si2O8：Eu2+ phosphor synthesized by the process was pure. The crystal structure of BaAl2Si2O8 transformed from hexagonal structure to monoclinic structure after precursor doping H3BO3，which changed the emission peak and luminescence intensity of BaAl2Si2O8：Eu2+ phosphor. The luminescence intensity firstly increased with H3BO3 doping concentration increasing，then decreased. The optimum mass fraction of H3BO3 is about 1.5%. The use of H3BO3 as flux could help the phosphor to crystallize，thus enhance the intensities of the excitation and emission spectra of BaAl2Si2O8：Eu2+ phosphor，improve the morphology of particles，and endow them with round edges，smooth surfaces and nearly spherical shapes.

Effect of H3BO3, BCl3, and BF3 pretreatments on oxidation of molten Al-Mg alloys in air

The effect of treating Al-Mg alloys with boron compounds on subsequent oxidation rates of the molten metal in air was determined by gravimetry. Untreated Al alloys containing 4.0–4.5% Mg gained over 10% weight, corresponding to complete consumption of Mg in spinel formation, in 75–100 hr in air at 750°C. Samples adequately treated before melting by dusting H3BO3 on the surface, by dipping in aqueous H3BO3 and drying, or by passing BCl3 (but not BF3) over the surface for 1 min gained less than 0.1% weight in up to 190 hr at 750°C. In all cases, B2O3 incorporated into the MgO surface film apparently provided this oxidation inhibition.