Modulation of Surface Ti-O Species in 2D-Ti3C2TX MXene for Developing a Highly Efficient Electrocatalyst for Hydrogen Evolution and Methanol Oxidation Reactions

Efficient visible-light-driven photocatalytic degradation of antibiotics in water by MXene-derived TiO2-supported SiO2/Ti3C2 composites: Optimisation, mechanism and toxicity evaluation

Photocatalytic technology has emerged as a promising solution to global water contamination, mainly through the effective degradation of persistent pharmaceutical pollutants. However, a few challenges still exist in enhancing degradation efficiency, reducing the toxicity of by-products, and ensuring cost-effective scalability. This study focuses on Tetracycline Hydrochloride (TCH) as an index antibiotic pollutant to evaluate the performance of a novel MXene-derived TiO2-supported SiO₂/Ti3C2 composite (SMXT) synthesized using ultrasonic and wet impregnation techniques. The SMXT-450 sample, annealed at 450 °C, exhibited a remarkable 95% degradation of TCH within 80 min, surpassing more complex three-component systems. The superior photocatalytic activities, validated through comprehensive characterisation tests, were found to stem from an optimized band gap, minimised electron-hole recombination, and enhanced charge transfer. The effective degradation process, primarily driven by •O₂⁻ and •OH radicals, was confirmed by trapping and ESR analysis. High-performance liquid chromatography (HPLC) and toxicity assessments also revealed that the intermediate degradation products are less harmful, further demonstrating the environmental sustainability of the formulated nanocomposites in treating antibiotic-polluted waters. This study's findings can highlight the potential of MXene-derived nanocomposites for the efficient remediation of antibiotic-contaminated water, offering a cost-effective and scalable approach to mitigating the impact of pharmaceutical pollutants on aquatic ecosystems.

MXene Electrocatalysts: Transformative Approaches in Hydrogen Production with Alternative Anode Reactions

Water electrolyzer is crucial for producing clean hydrogen, but the traditional approach faces challenges owing to the oxygen evolution reaction (OER) slow kinetics at the anode. Hybrid water splitting replaces the OER with the oxidation of an organic molecule to enhance hydrogen production along with value-added products. The scarcity of affordable and highly effective catalysts remains a major challenge. MXene, a 2D nanomaterial, has gained substantial attention for its enviable properties, for instance high conductivity, hydrophilicity, and substantial surface area. This review discusses experimental methods for synthesizing MXene and MXene-based nanocomposites. Furthermore, the small molecules oxidation such as benzyl alcohol, methanol, ethanol, urea, hydrazine, furfural, and formic acid as alternatives to the oxygen evolution reaction is examined. Finally, an understanding of imminent research and the development of MXene-associated materials in electrocatalytic applications are presented.

Ti3C2Tx MXene-supported ruthenium nanoclusters for efficient electrocatalytic hydrogen evolution

Developing an efficient and stable catalyst is both attractive and challenging for the electrochemical hydrogen evolution reaction (HER) due to the aggravation under the operating environment. MXene (Ti3C2Tx) is a potential catalyst support because of its abundant surface functional groups and unique hydrophilicity. However, anchoring noble metals onto MXene to construct high-performance electrocatalysts still presents some challenges. Herein, we present an MXene nanoparticle-supported Ru nanocluster (Ru@MXene-NP) electrocatalyst for HER. The Ru@MXene-NP not only effectively prohibits self-stacking but also ensures the full exposure of Ru nanoclusters. Thus, the Ru@MXene-NP catalyst exhibits an overpotential of 38.4 mV at 10 mA cm-2 and a Tafel slope of 26.4 mV dec-1 in an acidic medium, showcasing superior performance compared to most previously reported MXene-based catalysts. The small Tafel slope and low charge transfer resistance (Rct = 0.39 Ω) value indicate its fast electron transfer behavior. In addition, cyclic voltammetry curves and chronoamperometry tests demonstrate the high stability of Ru@MXene-NP. This work offers a novel perspective for designing catalysts by supporting noble metal nanoclusters on the MXene substrate's surface.

Unveiling the potential of MXene-fabricated catalysts: an effective approach for H2 generation from water splitting

Hydrogen has enough potential and can be successfully used as an alternative to the conventional fuel. It can be successfully produced from water that is not only a sustainable source but exists everywhere on earth. Additionally, its combustion releases water that is quite safe and environment friendly. The current project was designed to generate hydrogen from catalytic water splitting on TiO2@Ti3C2T x catalysts. To obtain the required catalytic characteristics, titania was engineered on Ti3C2T x surfaces in situ using an ethanol-assisted solvothermal approach. After careful recovery, the catalysts were characterized and assessed for the photoreaction. All photoreactions were performed in a quartz reactor (150 mL), where hydrogen evolution activities were monitored on GC-TCD (Shimadzu-JP). The comparative activities indicated that TiO2@C and TiO2@Ti3C2T x catalysts deliver 9.37 and 18.57 mmol g-1 h-1 of hydrogen, respectively. The higher activities of TiO2@Ti3C2T x were attributed to the existence of higher active sites (charge trapping centres) on the multilayer MXene that progressively promote and facilitate redox reactions. Reason is that existence of titania on MXene interfaces develops heterojunctions that rectify the charge transfer; hence reduce the charge recombination (i.e., back reaction). On the basis of encouraging activities, it has been concluded that the aforementioned approach holds promise to replace the costly and conventional hydrogen generation technologies.

Modification Strategies for Development of 2D Material-Based Electrocatalysts for Alcohol Oxidation Reaction

2D materials, such as graphene, MXenes (metal carbides and nitrides), graphdiyne (GDY), layered double hydroxides, and black phosphorus, are widely used as electrocatalyst supports for alcohol oxidation reactions (AORs) owing to their large surface area and unique 2D charge transport channels. Furthermore, the development of highly efficient electrocatalysts for AORs via tuning the structure of 2D support materials has recently become a hot area. This article provides a critical review on modification strategies to develop 2D material-based electrocatalysts for AOR. First, the principles and influencing factors of electrocatalytic oxidation of alcohols (such as methanol and ethanol) are introduced. Second, surface molecular functionalization, heteroatom doping, and composite hybridization are deeply discussed as the modification strategies to improve 2D material catalyst supports for AORs. Finally, the challenges and perspectives of 2D material-based electrocatalysts for AORs are outlined. This review will promote further efforts in the development of electrocatalysts for AORs.

Radiation-Induced Surface Modification of MXene with Ionic Liquid to Improve Electrochemical Properties and Chemical Stability

For the first time, an ionic liquid was grafted onto Ti3C2Tx MXene interlayers (MXene-g-IL) using a radiation technique. The IL was tightly immobilized on the surface of MXene nanosheets via chemical linkage, which exhibited excellent specific capacitance (160 F g-1 at 5 mV s-1) and improved structural stability (maintaining the sheet-like structure for 180 days). The facile, efficient, and scalable synthetic strategy derived from the radiation technique can open a new avenue for covalent functionalization of MXene-based materials and promote their further application.

Enhancing electrocatalytic methanol oxidation of Pd-Ir nanoalloy through electron-rich catalytic interface induced by incorporating phosphorus

Incorporating less expensive nonmetal phosphorus (P) into noble metal-based catalysts has become a developing strategy to enhance the catalytic performance of electrocatalysts for methanol electrooxidation reaction (MOR), attributing to the electronic and synergistic structure alteration mechanism. In the work, three-dimensional nitrogen-doped graphene anchoring ternary Pd-Ir-P nanoalloy catalyst (Pd₇IrP_x/NG) was prepared by co-reduction strategy. As a multi-electron system, elemental P adjusts the outer electron structure of Pd and diminishes the particle size of nanocomposites, which heightens the electrocatalytic activity effectively and accelerate MOR kinetics in alkaline medium. The study reveals that the electron effect and ligand effect induced by P atoms on the hydrophilic and electron-rich surface of Pd₇Ir/NG and Pd₇IrP_x/NG samples can reduce the initial oxidation potential and peak potential of CO_ads, showing significantly enhanced the anti-poisoning ability compared with commercial Pd/C as the benchmark. Meanwhile, the stability of Pd₇IrP_x/NG is significantly higher than that of commercial Pd/C. The facile synthetic approach provides an economic option and a new vision for the development of electrocatalysts in MOR.