Atomic-Distributed Coordination State of Metal-Phenolic Compounds Enabled Low Temperature Graphitization for High-Performance Multioriented Graphite Anode.

Continuous efforts have been made to achieve nanostructured carbon materials with highly ordered graphitic structures using facile synthetic methods. 3D graphite nanoballs (GNBs) are synthesized by the low-temperature pyrolysis of a non-graphitizable precursor, tannic acid (TA). Abundant phenol groups on TA bind to Ni2+ to form metal-phenolic coordination, which renders each Ni cation to be atomically distributed by the TA ligands. Even at low temperatures (1000 °C), highly ordered graphitic structure is promoted by the distributed Ni nanoparticles that act as a graphitization catalyzer. The crystallinity of the GNB is fully corroborated by the intense 2D peak observed in Raman spectroscopy. In particular, the graphitic layers have orientations pointing toward multidirections, which are beneficial for the rapid transport of Li-ions into graphite grains. The resulting materials exhibit outstanding electrochemical performance (120 mAh g-1 at 5 C and 282 mAh g-1 at 0.5 C after 500 cycles) when evaluated as a fast-chargeable negative electrode for lithium ion batteries.

Optimized antifouling γ-Al2O3/α-Al2O3 nanofiltration composite membrane for lignin recovery from wastewater.

This study focuses on the development of nanofiltration (NF) membranes with enhanced antifouling properties, high flux, and low molecular weight cut-off (MWCO) for the separation of lignin from paper mill wastewater. Using a sol-gel method by dip-coating, alumina hollow fiber membranes were fabricated with an interlayer to reduce surface roughness. The interlayer improved mechanical properties, effectively covering the surface irregularities and allowing for the subsequent application of a thinner functional layer. This approach significantly reduced surface roughness, from 112.6 nm to 62.9 nm, enhancing contamination resistance and lifetime. Characterization techniques, including X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM), and water contact angle measurements, confirmed the successful fabrication and enhanced properties of the membranes. The C2T6T3 membrane demonstrated the smallest roughness and the highest flux recovery rate (FRR) of 82.39% after cleaning with a 0.1 M NaOH solution. Performance evaluations showed that the developed membranes maintained high permeability (initial flux of 25.58 L·m⁻²·h⁻¹, decreasing to 14.06 L·m⁻²·h⁻¹ over time), achieved effective lignin rejection (consistently above 80%), and exhibited excellent long-term operational stability over 144 h of operation.

S- and N-Co-Doped TiO2-Coated Al2O3 Hollow Fiber Membrane for Photocatalytic Degradation of Gaseous Ammonia.

This study successfully prepared and tested sulfur- and nitrogen-co-doped TiO2-coated α-Al2O3 (S,N-doped TiO2/Al2O3) hollow fiber (HF) membranes for efficient photocatalytic degradation of gaseous ammonia (NH3). Thiourea was used as a sulfur- and nitrogen-doping source to produce a S,N-doped TiO2 photocatalyst powder. For comparative purposes, undoped TiO2 powder was also synthesized. Through the application of a phase-inversion technique combined with high-temperature sintering, hollow fibers composed of α-Al2O3 were developed. Undoped TiO2 and S,N-doped TiO2 photocatalyst powders were coated on the α-Al2O3 HF surface to obtain undoped TiO2/Al2O3 and S,N-doped TiO2/Al2O3 HF membranes, respectively. All prepared samples were characterized using XRD, TEM, XPS, UV-Vis, SEM, BET, FT-IR, and EDS. S and N dopants were confirmed using XPS and UV-Vis spectra. The crystal phase of the undoped TiO2 and S,N-doped TiO2 photocatalysts was a pure anatase phase. A portable air purifier photocatalytic filter device was developed and tested for the first time to decrease the amount of indoor NH3 pollution under the limits of the lachrymatory threshold. The device, which was made up of 36 S,N-doped TiO2/Al2O3 HF membranes, took only 15-20 min to reduce the level of NH3 in a test chamber from 50 ppm to around 5 ppm, confirming the remarkable performance regarding the photocatalytic degradation of gaseous NH3.

Al2O3-Based Hollow Fiber Membranes Functionalized by Nitrogen-Doped Titanium Dioxide for Photocatalytic Degradation of Ammonia Gas.

In recent years, reactive ammonia (NH3) has emerged as a major source of indoor air pollution. In this study, Al2O3-based hollow fiber membranes functionalized with nitrogen-doped titanium dioxide were produced and successfully applied for efficient heterogeneous photocatalytic NH3 gas degradation. Al2O3 hollow fiber membranes were prepared using the phase inversion process. A dip-coating technique was used to deposit titanium dioxide (TiO2) and nitrogen-doped titanium dioxide (N-TiO2) thin films on well-cleaned Al2O3-based hollow fiber membranes. All heterogeneous photocatalytic degradation tests of NH3 gas were performed with both UV and visible light irradiation at room temperature. The nitrogen doping effects on the NH3 heterogeneous photocatalytic degradation capacity of TiO2 were investigated, and the effect of the number of membranes (30, 36, 42, and 48 membranes) of the prototype lab-scale photocatalytic membrane reactor, with a modular design, on the performances in different light conditions was also elucidated. Moreover, under ultraviolet and visible light, the initial concentration of gaseous NH3 was reduced to zero after only fifteen minutes in a prototype lab-scale stage with a photocatalytic membrane reactor based on an N-TiO2 photocatalyst. The number of Al2O3-based hollow fiber membranes functionalized with N-TiO2 photocatalysts increases the capacity for NH3 heterogeneous photocatalytic degradation.

Novel TiO2/GO-Al2O3 Hollow Fiber Nanofiltration Membrane for Desalination and Lignin Recovery.

Due to its greater physical-chemical stability, ceramic nanofiltration (NF) membranes were used in a number of industrial applications. In this study, a novel NF membrane was prepared by co-depositing a titanium dioxide (TiO2) and graphene oxide (GO) composite layer directly onto a porous α-Al2O3 hollow fiber (HF) support. An 8 µm-thick TiO2/GO layer was deposited to the surface of α-Al2O3 HF support by vacuum deposition method to produce advanced TiO2/GO-Al2O3 HF NF membrane. Scanning electron microscope (SEM) micrographs, energy dispersive spectrometer (EDS), X-ray powder diffraction (XRD), thermogravimetric analyzer (TGA), porosity, 3-point bending strength, zeta potential analysis, and hydrophilic properties by water contact angle are used for TiO2/GO-Al2O3 HF NF membrane characterization. The results show that the developed membrane's MWCO ranged from 600 to 800 Da. The water flux, rejection of lignin, and sodium ions were 5.6 L/m2 h·bar, ~92.1%, and ~5.5%, respectively. In a five-day NF process, the TiO2/GO-Al2O3 HF NF membrane exhibits good lignin permeation stability of about 14.5 L/m2 h.