2D sodium titanate nanosheet encapsulated Ag2O-TiO2 p-n heterojunction photocatalyst: Improving photocatalytic activity by the enhanced adsorption capacity

In a photocatalytic reaction, maintaining the high efficiency of photocatalyst under a low concentration of pollutants is a key challenge. In this work, a new 2D sodium titanate nanosheet encapsulated Ag₂O-TiO₂ (2D NTO/Ag₂O-TiO₂) p-n heterojunction photocatalyst is proposed to deal with this dilemma. Through a simple plasma electrolytic oxidation (PEO) treatment and ion exchange treatment, a classic Ag₂O-TiO₂ p-n heterojunction structure is prepared and used as the photoelectric conversion unit in the photocatalyst. Then, through a subsequent hydrothermal treatment, a 2D NTO film that serves as the adsorption unit in the photocatalyst can be produced on the surface of the Ag₂O-TiO₂ p-n heterojunction layer. Finally, the desired 2D NTO/Ag₂O-TiO₂ structure is formed. The photocatalyst exhibits superior photocatalytic performance including high degradation rate as well as excellent catalytic stability and durability by combining the high sunlight utilization efficiency and high photoelectric utilization efficiency of the Ag₂O-TiO₂ p-n heterojunction and the outstanding adsorption performance of the 2D NTO film. Therefore, the problem of photocatalytic slow kinetics under low pollutants concentration is perfectly solved. This work provides a new strategy for the structural design of high-performance photocatalysts.     

Photo-electrochemistry of metallic titanium/mixed phase titanium oxide

In this study, the effect of potassium hydroxide concentration in anodization bath, anodization time, and calcination temperature on the photo-electrochemical behavior of metallic titanium/mixed phase titanium oxide is investigated. Further, the phase structure of a titanium oxide photocatalyst prepared on a titanium electrode through a high-voltage anodization method is examined. The study exploits photo-electrochemical, Fourier transform infrared spectroscopy attenuated total reflectance (FTIR–ATR), X-ray diffraction, and Raman spectroscopic methods to obtain better insights into the mechanism of mixed-phase titanium oxide formation. In this regard, the photo-electrochemical properties of the photocatalysts prepared in single excitation energy, violet light (410 nm), were investigated. The anodization time and the potassium hydroxide concentration in the anodization bath have significant effects on the photo-electrochemical properties of the photocatalysts. The experiments show that the effect of potassium hydroxide concentration is a function of the anodization potential applied, demonstrating different patterns as the anodization potential changes. Furthermore, FTIR-ATR, X-ray diffraction, and Raman spectroscopic studies reveal that the extended anodization times decrease the population of OH-containing groups, leading to lower photo-electrochemical performance. On the other hand, the formation of anatase phases becomes more favorable only in the extended anodization times before application of the calcination process. Additionally, the calcination temperature has a significant impact on the anatase to rutile ratio. Finally, increasing potassium hydroxide concentration leads to the formation of an amorphous titanium oxide layer. It can be concluded that the obtained information might have a significant impact on the preparation of titanium oxide and other metal oxide photocatalysts through the high voltage anodization process.     

The effect of titanium dioxide-supported CdSe photocatalysts enhanced for photocatalytic glucose electrooxidation under UV illumination

The wetness impregnation method was used to synthesize 0.1% CdSe/TiO₂ photocatalysts with different atomic molar ratios (90–10, 70–30, 50–50, and 30–70). These catalysts were characterized by XRD, SEM-EDX and mapping, TEM-EDS, UV–VIS spectroscopy, fluorescence spectroscopy, XPS, TPR, TPO, and TPD analyses. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) analyses were performed to examine the photocatalytic activity for photocatalytic fuel cells (PFCs) in glucose solution in the dark and under UV illumination. The characterization analyses revealed that anatase TiO₂ formed the catalyst and electronic structure and surface properties changed when doped with metal. The photocatalytic glucose electrooxidation (PGE) results demonstrate that the 0.1% CdSe(50-50)/TiO₂ catalyst has higher photocatalytic activity, stability, and resistance than other catalysts both in the dark (2.71 mA cm^?2) and under UV illumination (7.20 mA cm^?2). These results offer a promising new type of photocatalyst for PFC applications.     

TiCN MXene hybrid BCN nanotubes with trace level Co as an efficient ORR electrocatalyst for Zn-air batteries

Developing non-noble metal oxygen reduction reaction (ORR) electrocatalysts with high performance, excellent stability, and low-cost is crucial for the industrialization of fuel cells. Herein, trace level Co modified 3D hybrid titanium carbonitride MXene and boron-carbon-nitrogen nanotubes catalyst (TiCN–BCN–Co) is fabricated by spray-lyophilization and high-temperature pyrolysis. This strategy not only avoids the oxidation of Ti₃C₂T_x MXene, but also introduces nitrogen atoms into the titanium carbide lattice to form a more electrocatalytically active TiCN crystal phase. The obtained TiCN–BCN–Co exhibits superior ORR catalytic activity with a positive half-wave potential of 0.83 V vs. RHE and outperforms commercial Pt/C in terms of stability and methanol tolerance. Impressively, the Zn-air battery with TiCN–BCN–Co cathode achieves a superior specific capacity of 791 mAh g^?1 and long-term stability of 200 h.     

Insight into tribological and corrosion behaviour of binderless TiCxNy ceramic composites processed via pulsed electric current sintering technique

The study presents the corrosion behaviour and wear response of pulsed electric current sintered binderless TiC₅₀N₅₀, TiC₇₀N₃₀, and TiC₉₀N₁₀ based ceramic composites, consolidated by spark plasma sintering (SPS), and the relative densities were evaluated using the Archimedes principle. The microstructural evolutions of the sintered samples were examined through various microscopy techniques, and their susceptibility to corrosion in aggressive chloride environment was assessed using open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The microstructural examination of the specimens showed the presence of different phases within the titanium carbonitride (TiCN) cermets. The wear resistance evaluated using the frictional coefficient (COF) and calculated wear rate showed that the specimens exhibited an improved resistance. The specimens further showed enhanced resistance to corrosion in the test electrolyte, as the TiC₅₀N₅₀ cermet displayed enhanced resistance to the aggressive chloride ions in comparison to the other specimens.     

浅论白马铁矿建设条件

从矿石选别性能，外部运输条件，伴生金属以及矿山建设的前期准备工作情况等多方面综合论述了白马铁矿建设的有利条件     

钛铁矿制备纳米钛基材料的研究

以廉价易得的天然钛铁矿为原料,采用"机械球磨活化+碱浸"工艺制备FeTiO_3纳米花,采用"机械球磨活化+碱浸+酸浸"工艺制得TiO_2/FeTiO_3纳米微粒。首先通过机械球磨活化减小钛铁矿的物理尺寸,使其化学性质变得活泼,然后通过碱浸的方法得到呈三维花瓣状的FeTiO_3纳米花,最后纳米花进一步酸浸得到规则的TiO_2/FeTiO_3纳米微粒。通过分析FeTiO_3纳米花和TiO_2/FeTiO_3纳米微粒的形貌和物相组成,得出结论碱浸时较优的NaOH浓度为1mol/L,碱浸时间为2h,酸浸时较优的HCl浓度为2mol/L,酸浸时间为8h。较优条件下获得的FeTiO_3纳米花厚度在25nm左右,长度在200～400nm之间,TiO_2/FeTiO_3纳米微粒直径在30nm左右。通过分析碱浸和酸浸的机理,可知反应过程中都有不稳定液相中间产物的生成,运用溶解和中间体水解产生沉淀的机理进行了解释,中间体的生成和水解平衡受酸或者碱浓度的影响。     

Application of electrooxidation process for treating concentrated wastewater from distillery industry with a voluminous electrode

Experiments in a laboratory scale were carried out to reduce color and chemical oxygen demand (COD) in distillery wastewater by using electrooxidation processes. A cylindrical electrochemical reactor constructed in an axial configuration with 0.2m diameter and 0.35 m height was employed in this study. Two materials including graphite particles and titanium sponge were used as the voluminous anodes. A cathode made from Ti/RuO(2) was placed 0.04-0.05 m above the upper level of anode particles. Effect of parameters including initial pH of wastewater (1-5), time of dilution, current intensity (1-10A), type of additive (H(2)O(2) and NaCl), and additive concentration were investigated. The results indicated that the anode made from titanium sponge showed a higher potential to treat wastewater than the another one. The treatment in acidic condition (pH=1) provided the maximum oxidation of organic pollutants in wastewater. The presence of additives can promote the reduction of COD and color in wastewater approximately 89.62% and 92.24%, respectively. The maximum current efficiency was reached at the first 30 min and decreased slightly as electrolysis time proceeded due to the formation of passivation on the electrode surface. The energy consumption was obtained in the range of 2.82-4.83 kWh/kgCOD or 24.08-28.07 kWh/m(3) wastewater depending upon the concentration of additive. The kinetics of COD reduction was the pseudo first-order reaction with a fast rate constant of 6.78 min(-1).