Glycerol is an important by-product in the production process of biodiesel with low prices and abundant reserves.Converting glycerol into high value-added fine chemicals is one of the effective ways to alleviate the current problems of resources and environment.Glycerol electrooxidation reaction（GEOR） has great application prospects due to its advantages of no need for oxidants and generation of clean energy H₂ at the cathode.However，the high cost and scarcity of precious metal catalysts limit their commercial application.Therefore，there is an urgent need to develop efficient non-noble metal catalysts to replace noble metal catalysts.Based on a brief introduction of glycerol oxidation mechanism，recent research on transition metal-based GEOR catalysts and various catalyst design strategies to enhance glycerol oxidation performance were reviewed.These strategies included doping engineering，alloy strategies，heterogeneous structure building，composite engineering and crystal phase adjustment.Finally，the challenges faced by transition metal-based catalysts in GEOR were prospected.

As a traditional electrode material，graphite felt（GF） has a unique three-dimensional porous structure and good electrical conductivity，however，it has inherent defects such as poor surface wettability and insufficient electrochemical activity.To address these problems，the researchers focused on the activation of the graphite felt substrate by introducing specific functional groups or nanostructures using physical，chemical and electrochemical methods in order to develop composite electrode materials with superior properties for applications in the field of efficient energy storage.Based on the introduction of graphite felt characteristics and energy storage mechanism，the modification advantages of transition metal compounds，conducting polymers and carbonaceous materials on GF substrates，and doping with heteroatoms（O，S，N，etc.） to regulate the surface wettability，conductivity and electrocatalytic activity of GF were reviewed.Furthermore，the application prospect of GF composite materials in wearable devices and lightweight energy storage devices was highlighted.Meanwhile，it was also pointed out the challenges of GF composites in the precise regulation of the preparation process.In the future，with the continuous development of material science，surface treatment technology and electrochemical theory，GF surface modification was expected to emerge more innovative technologies and provide theoretical support for the commercial application of supercapacitors.

Cold precipitation crystallization is one of the common methods to produce crystalline magnesium sulfate，but the obtained magnesium sulfate crystals often have irregular morphology and rough surface，which limits the application of magnesium sulfate crystals in the field of coatings and composites.In this paper，the effect of common ions Li⁺、K⁺、Ca²⁺ in raw brine on the micro-morphology of crystallized magnesium sulfate was studied to better meet the needs of subsequent applications.According to the process of extracting high-purity magnesium sulfate hydrate by cold precipitation method，the mesostable solution and crystalline products were characterized in the static crystallization of MgSO₄-NaCl co-saturated solution.The results showed that NaCl was adhered to the crystalline surface during the cooling process affecting the crystal morphology.The impurity ions would increase the ratio of solvent-sharing ion pairs（Mg²⁺-H₂O-SO₄^2-），which was more favorable for the growth and precipitation of MgSO₄·6H₂O.While the composition of the cooling crystallization products was not changed，the impurity ions would contribute to the reduction of Na content on the crystal surface and optimize the crystal morphology.When the content of K₂SO₄ was 300 mmol/L，the Na content of the products could be reduced from 0.57% to 0.03%，and a regular crystalline product was obtained.It was hypothesized that the impurity ions would compete with Na⁺ for the crystallization sites located on the crystal surface，preventing the nucleation of the sodium salt，and molecular dynamics simulations were used to verify the above speculation.Therefore，the presence of a small amount of impurity ions in solution was conducive to to obtain magnesium sulfate crystals with smooth surface and stable properties.

The preparation of battery-grade iron phosphate using air as oxidizing agent has the problems of large particle size and low efficiency with traditional mechanical stirring reactor and bubbling reactor.In this study，it was proposed to prepare battery-grade iron phosphate by using jet-enhanced air oxidation，using a self-developed jet oxidation reactor as the experimental setup，and air as the oxidizing agent for the oxidative precipitation of ferrous dihydrogen phosphate solution.It was found that the jet-enhanced air oxidation method could preferably prepare battery-grade iron phosphate.In addition，the effects of reaction temperature，reaction time，reactant flow rate，air flow rate and pH on the particle size and yield of the product during the preparation of iron phosphate were investigated by the method of orthogonal test.The synthesized products were characterized and analyzed by X-ray diffraction，laser particle size analyzer and scanning electron microscopy.The results showed that the optimum process conditions were reaction temperature of 90 °C，reaction time of 100 min，ferrous dihydrogen phosphate solution flow rate of 10 L/min，air flow rate of 3.5 L/min，and pH of 2.0.Under these conditions，the prepared ferrous phosphoric acid was a spherical-like particle，with a high degree of crystallinity，a narrow particle size distribution，and the D₅₀ was 5.37 μm，the yield was 93.28%.

To investigate the high-temperature crystalline phase transitions of tin-based perovskites and the relationship between surface active sites such as acidic and basic sites，a series of ASn（OH）₆（A=Ca，Sr，Ba） precursors were prepared by hydrothermal method，and pure phase ASnO₃（A=Ca，Sr，Ba） perovskite-type composite oxides were obtained by calcination under 800 ℃ under air atmosphere.The bulk and surface structure of these samples were characterized using techniques such as XRD，FTIR，Raman，XPS，and TEM.The results showed that CaSnO₃ and SrSnO₃ were orthorhombic phases，while BaSnO₃ exhibited a cubic phase with Schottky defects.As the temperature increased from room temperature to 800 ℃，CaSnO₃ and BaSnO₃ did not undergo any crystalline phase transition，while SrSnO₃ transformed from orthorhombic phase（Pnma） to orthorhombic phase（Imma） at high temperatures.Their surface acid-base sites were closely related to the alkalinity of A-site cations.The results showed that the stronger the alkalinity of A-site cations，the richer the basic sites，and the fewer the acidic sites.The moderate basic site was related to the concentration of oxygen vacancies.The concentration of oxygen vacancies depended on the average metal oxygen bond energy.The lower this bond energy，the more abundant oxygen vacancies and moderate basic sites.Floody-type composite oxide was an excellent oxygen ion conductor，which showed good response performance in some aerobic multi-phase catalytic reactions.The cleptication of its high temperature phase change and surface activity position was conducive to further understand their research on the research relationship in this type of reaction.

La_0.15Y_0.85-x Nd _x Ni_3.2Mn_0.15Al_0.15（x=0~0.6） hydrogen storage alloy for automotive battery anode was prepared by replacing Y with A-end Nd element.The phase structure，microstructure，and electrochemical performance of hydrogen storage alloys with different Nd contents replacing Y were investigated.The results showed that when x=0~0.3，the hydrogen storage alloy was mainly composed of Ce₂Ni₇ and LaNi₅ phases，when x≥0.4，the hydrogen storage alloy was mainly composed of Ce₂Ni₇ and PuNi₃ phases.As the x value increased from 0 to 0.6，the cell parameters a and c of the hydrogen storage alloy gradually was increased，while c/a was gradually decreased.After replacing Y with different contents of Nd，hydrogen storage alloy electrodes could achieve maximum discharge capacity（C_max） after 2~3 activations.C_max had a linear correlation with the abundance of Ce₂Ni₇ type phases in the hydrogen storage alloy.The higher the abundance of Ce₂Ni₇ type phases，the greater the C_max of the hydrogen storage alloy.As the x value increased from 0.2 to 0.6，the S₁₀₀ of the hydrogen storage alloy was firstly increased and then decreased.The S₁₀₀ of the hydrogen storage alloy with added Nd element was higher than that of the hydrogen storage alloy without Nd addition.Moreover，the x=0.4 hydrogen storage alloy had a high S₁₀₀ and a large discharge capacity.The cycling stability of the hydrogen storage alloy electrode was mainly determined by its corrosion resistance in alkaline solution.At the same discharge current density，the high rate discharge performance of hydrogen storage alloys was highest at x=0.4.The high rate discharge performance of hydrogen storage alloy electrodes was mainly determined by the hydrogen diffusion coefficient D₀ when x=0 and 0.1，and determined by the exchange current density I₀ and hydrogen diffusion coefficient D₀ when x=0.2~0.6.

In order to study the thermal runaway characteristics of lithium-ion battery modules in high temperature environment，based on the equation of energy conservation and the heat generation equation of side reactions，a three-dimensional numerical model of lithium-ion battery modules was established，and key physical processes such as temperature distribution，heat transfer，and heat generated by the side reactions within the battery modules were simulated，and the effect of parameters such as ambient temperature，heat transfer coefficient，initial temperature on the thermal runaway of lithium-ion battery modules was analyzed.The results showed that as the ambient temperature rised，more heat was generated inside the battery modules due to the accelerated rate of chemical reactions.When the ambient temperature reached 140 ℃，with heat transfer coefficients of 10 W/（m²·K），15 W/（m²·K） and 25 W/（m²·K），the heat of these reactions became quantitatively larger，and leaded to the occurrence of thermal runaway of the battery.Further，when the ambient temperature was 170 ℃，the heat transfer coefficients were 5 W/（m²·K） and 25 W/（m²·K），the thermal runaway of the battery module occured around 16 200 s and 4 600 s，respectively，and the peak temperature of thermal runaway was around 375 ℃.When the ambient temperature was 170 ℃，the initial temperature was 20 ℃ and 100 ℃，the thermal runaway of the battery modules occured around 9 280 s and 3 980 s，respectively，and the peak temperature of the thermal runaway was around 380 ℃.It showed that under the high temperature environment，the higher of the initial temperature and the higher of the heat transfer coefficient，the earlier thermal runaway occured，but both the initial temperature and the heat transfer coefficient had little effect on the peak temperature of the thermal runaway.

The viscosity，solid content，and stability of lithium iron phosphate slurry are important parameters in the battery manufacturing process，which will directly affect the quality of the coated electrode plates and ultimately affect the performance and lifespan of the battery.A series of lithium iron phosphate materials（LFP/C） coated with different carbon sources were prepared using high-temperature solid-phase method，and their physical，electrochemical and processing properties were studied.The XRD results showed that the LFP/C samples prepared with three organic compounds as carbon sources all exhibited high crystallinity，and no obvious impurities were found.The Raman results showed that the carbon layer graphitization degree of LFP/C-3 sample coated with sucrose as the carbon source was the highest.The SEM and TEM results demonstrated that the LFP/C-3 sample had the smallest primary particle size and good particle dispersion，with a carbon layer thickness of about 5 nm and good coating uniformity.The electrochemical characterization results showed that the discharge specific capacity of LFP/C-3 sample reached 154.6 and 130.9 mA·h/g at 0.1C and 1.0C rate，respectively，and had excellent rate performance.After 110 cycles at 1.0C rate，the capacity retention rate was as high as 98.2%.However，the LFP/C-1 sample coated with glucose as the carbon source showed the best processing performance.Under the same solid content conditions，the initial slurry viscosity was 10 738 mPa·s.The three-stage thixotropy test results showed a viscosity recovery rate of 97.86%.The results provided some reference significance for the selection of carbon sources in the industrial production of lithium iron phosphate.

China has abundant barium ore resources，but some specialized high-purity barium materials still rely on imports.In order to enhance the international competitiveness of products and achieve safe and controllable industrial supply chain，research was conducted on the production process of high-purity barium hydroxide.The crystallization temperature of barium hydroxide in different solution compositions was mainly measured.Further，through orthogonal experimental design and response surface curve analysis，the effects of barium chloride mass fraction，insulation time，and stirring speed on the crystallization of barium hydroxide were investigated to obtain the optimal process conditions.Finally，high-purity barium hydroxide was obtained through recrystallization.The results showed that the optimal process for single crystallization was w（BaCl₂· 2H₂O） at 27.32%，insulation time of 2.1 h，stirring speed of 306 r/min，laboratory chloride ion at 0.015%，corresponding to 0.017% of the production line product chloride ion，which met the chemical purity requirements of "Reagent grade barium hydroxide octahydrate"（HG/T 2629—2011）.When w［Ba（OH）₂·8H₂O］ was 42.85%，the insulation time was 2.0 h，and the stirring speed was 306 r/min，high-purity barium hydroxide with chlorine content of 0.000 7%，magnesium content of 0.000 6%，calcium content of 0.000 5%，iron content of 0.000 1%，and strontium content of 0.000 9% could be produced，and the product yield could reach over 91.87%.This study was aimed to optimize and improve the production process of high-purity barium hydroxide，which could effectively enhance technical requirements，reduce costs and increase efficiency，enhance product international competitiveness，and meet the needs of upgrading and developing the electronic new materials industry chain.

Thermodynamic analysis is an important means of studying chemical reactions.The possible occurrence of chemical reactions in the reaction system and effect of reaction conditions on equilibrium compositions are predicted by conducting thermodynamic analysis.In order to reveal the mechanism of FeS₂-FeSO₄ reaction system for preparing iron oxide and theoretical basis for the preparation of material，thermodynamic analysis of FeS₂-FeSO₄ reaction system was performed by HSC Chemistry software.The analysis results according to the ∆_rG^⊖ and chemical equilibrium composition of the reaction process at different temperatures showed that R1~R2 reaction were undergone to generate α-Fe₂O₃ and Fe₃O₄ in the FeS₂-FeSO₄ reaction system within the temperature of 450 ℃，and the generated Fe₃O₄ reacted with FeSO₄ to form α-Fe₂O₃ base on R12 reaction.But at this temperature，R1~R2 reaction were incomplete.The thermodynamic analysis showed that R1~R2 were all endothermic reactions，and the ∆_rG^⊖ of R1 was less than that of R2 and equilibrium constant of R1 was greater than that of R2 at the same temperature，indicating that it was more conducive to the R1 reaction.When the temperature was rised to 500 ℃，R1~R2 reaction could proceed relatively completely.In addition，the produced Fe₃O₄ could be fully reacted with FeSO₄ to form α-Fe₂O₃ by controlling FeSO₄/FeS₂ ratio（13∶1），which was greater than the theoretical ratio of reaction R1.Based on thermodynamic analysis，α-Fe₂O₃ with the mean diameter of 62 nm was successfully synthesized by solid-phase reduction method at 500 ℃ for 60 minutes with the FeSO₄/FeS₂ ratio of 13∶1.From this，it could be seen that thermodynamic analysis of the FeS₂-FeSO₄ reaction system provided theoretical basis for the preparation of α-Fe₂O₃ nanoparticles.

Carbon materials for supercapacitor electrode materials were prepared using biomass waste wood chips as raw materials by phosphoric acid method and phosphoric acid-sulfuric acid synergistic activation method.Characterization and analysis of the microstructure，chemical composition，and degree of graphitization of biochar were carried out using techniques such as BET，FT-IR，XPS，XRD，and Raman.The results showed that the optimal preparation process conditions were impregnation ratio of 2.0∶1，heating rate of 10 ℃/min，activation temperature of 550 ℃，and activation time of 60 min.The specific surface area of phosphoric acid based wood chip carbon material was 1 717 m²/g，total pore volume was 1.00 cm³/g，microporous pore volume was 0.83 m³/g，and mesoporous pore volume was 0.17 m³/g.The specific surface area of wood chip based carbon material（MSC-4-98） using phosphoric acid-sulfuric acid synergistic activation method was 1 951 m²/g，with a total pore volume of 1.66 cm³/g，a microporous pore volume of 0.60 m³/g，and a mesoporous pore volume of 1.06 m³/g.The results of XPS tests indicated that carbon materials had a high degree of graphitization.According to electrochemical performance tests，the specific capacitance of MSC-4-98 was 250.38 F/g at a current density of 0.5 A/g.When the current density was further increased to 2.0 A/g，the specific capacitance still reached 204.56 F/g，remaining at 81.7% of the highest specific capacitance，with high specific capacitance and good capacitance retention.Although the wood chip carbon material prepared by the phosphoric acid method had a high specific surface area and high porosity，the underdeveloped mesopores did not meet the requirements of electrode materials.The wood chip based carbon materials prepared with phosphoric acid and sulfuric acid had high specific surface area，well-developed and balanced mesopores，and excellent electrochemical performance，which had great potential in the application of supercapacitors.

In order to improve the resource utilization rate of phosphogypsum，the modified hemihydrate phosphogypsum wall materials（MPGWM） was prepared by adding quicklime and melamine water reducing agent（SM） to hemihydrate phosphogypsum（HPG）.The control variable method was used to study the effect of water-cement ratio and water reducing agent content on the mechanical properties of MPGWM，combined with the multiple regression model to analyze the variation rule of the mechanical properties of MPGWM under the action of two-factor coupling，and to obtain the optimal ratio of the high content modified hemihydrate phosphogypsum wall materials.The results showed that the main failure characteristics of the cubic compressive strength test of high content MPGWM specimens were splitting failure and conical failure，and the failure pattern of the cubic splitting tensile test was typical splitting failure.The apparent density of the specimens was mainly derived from HPG and quicklime.The apparent density and mechanical properties of MPGWM specimens were greatly affected by water-cement ratio，followed by the amount of water reducing agent.When the content of SM was 1.0% and the water-cement mass ratio was 0.29，the cube compressive strength of the specimens could reach 27.87 MPa.When the content of SM was 1.0% and the water-cement mass ratio was 0.32，the splitting tensile strength could reach 1.92 MPa.Through regression analysis，the optimal mix ratio of MPGWM was predicted to be 97%（mass fraction） HPG，3% quicklime，water-cement mass ratio of 0.27，and water reducer dosage of 1.2% of the HPG and quicklime mixture.The research results could provide reference for the resource utilization of phosphogypsum and promote the sustainable development of phosphorus chemical enterprises.

In order to explore the effect of coal gangue powder on the properties of modified magnesia sulfide cement before and after calcination，coal gangue powder was firstly calcined at different temperatures（0，600，800 ℃），and then mixed as aggregate to prepare modified magnesia sulfide cement，and X-ray diffraction，scanning electron microscopy and mercury injection instrument were used to test the phase composition，microscopic morphology and porosity of the cement.The effects on mechanical properties，water and acid resistance，micro-morphology and pore structure of modified magnesium sulfide cement were analyzed.The test results showed that the addition of coal gangue powder calcined at 800 ℃ could improve the compressive strength of the modified magnesium sulfide cement.When the addition amount was 15%，the maximum compressive strength of the cement at 28 days，which was 130% of the reference sample.At the same time，the water and acid resistance of the cement could be improved.The addition of coal gangue powder could improve the microstructure of modified magnesia sulfide cement，promote the growth of 5·1·7 phase，and make the morphology more dense.20%EG/MOS after leaching，the proportion of pore size greater than 100 nm was decreased，and the proportion of pore size less than 10 nm was increased，indicating that the addition of coal gangue powder calcined at 800 ℃ mass 20% could resist the penetration and dissolution of water and acidic liquid，and strengthen the water resistance and stability of the cement.

In order to reduce the energy consumption of COD removal by carbonization of waste salt，metal catalyzed organic cracking technology was used.The process of COD removal by Cu²⁺ catalyzed carbonization of waste salt was studied.The effects of Cu²⁺ dosage，reaction temperature and reaction time on COD removal in the carbonization process of waste salt were investigated.The response surface method was used for modeling optimization and verification.The results showed that the effect of COD removal by Cu²⁺ catalyzed carbonization of waste salt was obvious，and higher COD removal rate could be obtained at lower temperature.When the catalyst was not added，the COD removal rate of the waste salt carbonized at 550 ℃ was 90.45%.After adding the catalyst，the COD removal rate of the waste salt carbonized at 350 ℃ could reach 92.20%，so the temperature reduction effect was remarkable.The significant factors affecting COD removal rate from high to low were Cu²⁺ dosage，reaction temperature and reaction time.The response surface method was used to optimize the mathematical model established by waste salt carbonization.The fitting value was in good agreement with the verification test results.The optimal process parameters after optimization were as follows：the amount of Cu²⁺ was 0.4%，the reaction temperature was 450 ℃，and the reaction time was 0.7 h.At this time，the predicted COD removal rate was 98.53%.Through three experiments，the average COD removal rate was 98.55%，which was 0.02% different from the model，indicating that the optimization conditions were accurate and reliable.

The existence of impurities such as silicon and organic matter in phosphogypsum seriously restricts the value-added utilization of phosphogypsum.Based on this，phosphogypsum as the by-product of a phosphorus chemical enterprise in Hubei Province was studied.The removal of impurities such as quartz and organic matter in phosphogypsum was studied by synchronous reverse flotation combined with pre-screening process，using octadecyl trimethyl ammonium chloride（1831） as desilication agent.The mechanism of 1831 was investigated by XRD，Zeta potential，contact Angle and XPS analysis.The results showed that the process combined with pre-screening and synchronous reverse flotation could effectively improve the quality of phosphogypsum concentrate.Under the optimal process conditions of screening at 178 μm，decolorizing agent TC-3 of 600 g/t，decolorizing agent 1831 of 100 g/t and rotating speed of 1 800 r/min，phosphogypsum concentrate could be achieved with the CaSO₄·2H₂O content of 94.543% and whiteness of 58.07%.The mechanism analysis showed that 1831 formed selective adsorption on quartz surface through hydrogen bonding，and then significantly enhanced the hydrophobicity and floatability of quartz.

In order to solve the antibiotic wastewater pollution and indoor decoration low concentration formaldehyde pollution，activated carbon supported g-C₃N₄/TiO₂（g-C₃N₄/TiO₂/AC） composite photocatalyst was prepared by a simple mixed high temperature calcination method.The crystal phase，elemental composition，microstructure，spectral response range and photogenerated carrier recombination of the composite photocatalyst were characterized by XRD，XPS，TEM，UV-vis DRS and PL techniques.The bending band and internal electric field of S-scheme heterojunction realized the efficient separation of photogenerated carriers，broadened the spectral absorption range，and effectively retained the active groups such as ·O₂^-，h⁺ and ·OH，showing excellent degradation activity and stability of sulfamethoxazole（STZ）.Under the conditions of 1.0 mg g-C₃N₄/TiO₂/AC dosage and 100 mg/L STZ initial concentration，the degradation rate of STZ was 98.8% within 30 min under visible light irradiation，which was significantly better than that of g-C₃N₄，TiO₂ and TiO₂/AC.Photocatalytic coatings were synthesized by doping g-C₃N₄/TiO₂/AC into epoxy resin coatings.Photocatalytic concrete was uniformly sprayed onto the surface of concrete by air spray gun.Photocatalytic concrete showed good formaldehyde degradation activity and stability.The loading of g-C₃N₄/TiO₂/AC was 3%，the initial concentration of formaldehyde was 1 000 mg/L，and the degradation rate of formaldehyde reached 96.3% within 180 min of visible light irradiation，which effectively realized the efficient degradation of low concentration formaldehyde gas in interior decoration.

In order to achieve efficient degradation of formaldehyde in buildings，AgBr/C₃N₅ composites were prepared by using AgNO₃，C₃N₅ and cetyltrimethylammonium bromide as precursors.The composites were characterized by X-ray patterns diffraction（XRD），Fourier transform infrared spectroscopy（FT-IR），UV-visible diffuse reflectance spectroscopy（DRS），steady-state fluorescence spectroscopy（PL），transmission electron microscopy（TEM），transient photocurrent spectroscopy（TPC） and electrochemical impedance spectroscopy（EIS）.Using metakaolin and phosphoric acid modified water glass as the main film-forming material，sodium hexametaphosphate as the dispersant，tributyl phosphate as the defoamer，sodium dodecyl sulfate as the surfactant，carboxymethyl cellulose as the emulsifier，the prepared AgBr/C₃N₅ composite material as the functional component，the AgBr/C₃N₅ inorganic photocatalytic coating was prepared by mechanical mixing method.The AgBr/C₃N₅ inorganic photocatalytic coating was loaded on the surface of concrete by spraying to study its degradation activity and stability of HCHO gas in the building.The results showed that the AgBr/C₃N₅ composite material had a wide spectral response range，efficient photoelectron-hole separation，high specific surface area and low charge mass transfer resistance to achieve efficient and stable photocatalysis.The AgBr/C₃N₅ inorganic photocatalytic coating with a mass fraction of 5% was sprayed on the surface of concrete.After 7 d of visible light irradiation，the degradation rate of HCHO reached 91.50%，showing excellent HCHO degradation activity.The degradation rate of HCHO was still higher than 90% after 10 times of recycling，showing good durability.