Ke Wei,Jiu-Xiang Yang,Fang-Yuan Bai,Yuan-Sheng Shen,Kai Liu,Jing Liu,Li-Hua Chen,Yu Li,Bao-Lian Su
Ti3C2 MXene has been extensively studied in the field of photocatalytic hydrogen production since its discovery due to the large specific surface area and adjustable surface groups. However, the weak interaction at the interface of Ti3C2-based composites leads to a high energy barrier, which is not conducive to carrier transport. Herein, we propose the construction of a sandwich Ti3C2/R-TiO2 composite photocatalyst by in situ growing rutile TiO2 (R-TiO2) nanoneedles in Ti3C2 MXene through NaOH oxidation treatment and the microwave hydrothermal method. This in situ synthesis can make Ti3C2 MXene and TiO2 nanoneedles closely link together, which is conducive to carrier transport and material stability. The best Ti3C2/R-TiO2 composite achieves an excellent hydrogen production rate of 1.62 mmol g–1 h–1, as endowed by the 2D nanosheet-constructed sandwich structure, an increased specific surface area, and improved charge carrier separation and transport.
Gu Huang,Hewei Si,Lilan Zou,Haoran Zhang,Jianjun Liao,Shiwei Lin
A self-powered photoelectrochemical (PEC) sensor based on a Ti3O/rutile TiO2 (Ti3O/R-TiO2) heterophase junction nanocomposite is constructed for a highly sensitive and specific detection of tetracycline (TC). The Ti3O/R-TiO2 heterophase junction is successfully grown in situ on a Ti substrate via a one-step calcination method. XRD and Rietveld refinement results confirm that the contents of Ti3O and R-TiO2 can be tuned by the adjustment of the calcination temperature. Benefiting from the improved generation and separation of photogenerated electron–hole pairs as a result of the introduction of metallic phase Ti3O and heterophase junction, the Ti3O/R-TiO2 photoelectrode prepared at 700 °C (Ti3O/R-TiO2-700) and beyond presents much higher photocurrent density than the photoelectrode with pure R-TiO2 under light irradiation. More importantly, a self-powered PEC sensor with good performance was constructed for TC detection by using Ti3O/R-TiO2-700 as a photoelectrode. This PEC sensor displays a wide working range (3–300 μM) and a low detecting limit (0.039 μM) as well as good sensitivity. Additionally, a possible charge separation mechanism over the Ti3O/R-TiO2 heterophase junction is also proposed. This work provides valuable insight into the design and development of high-performance photoelectrodes through the modulation of crystal phases in nanocomposites for highly effective chemical sensors.
Despite the potential of sonodynamic therapy (SDT) in treating malignant tumors, the lack of effective sonosensitizers has limited its clinical implementation. In this study, we explored the relationship between the heteroatom doping concentration in metal–organic frameworks and interface formation after pyrolysis by regulating the addition of manganese sources and successfully derived Z-scheme heterojunctions MnxOy/(A/R)TiO2 (MTO) in situ from MIL-125-NH2 (Ti/Mn). The electron transfer pathway introduced by interfacial contact promoted carrier separation and greatly preserved the effective redox components, significantly influencing the performance of reactive oxygen species generation. Upon reaching the tumor sites, MTO effectively depleted glutathione to alleviate the suppressive tumor environment, and the heterojunctions and MnxOy in MTO facilitated SDT and synergistic chemodynamic therapy (CDT), respectively, leading to enhanced immunogenic cell death (ICD). Furthermore, Mn2+ uptake by dendritic cells (DCs) and the tumor-associated antigens released due to ICD activated the stimulator of interferon genes pathway, which elicited a robust tumor-specific immune response by driving the maturation of DCs and the activation of T cells. In addition, the activated T cells secreted high levels of interferon-γ to enhance Mn3+/Mn2+-mediated ferroptosis in metastatic tumor cells. The combination of MTO-mediated synergistic therapy and PD-L1 checkpoint blockade exhibited vaccine-like functions, inducing stronger systemic immunity and durable immune memory to inhibit tumor progression, metastasis, and recurrence. To summarize, we synthesized a self-enhancing nanoplatform for synergistic SDT/CDT/immunotherapy using multifunctional MOF-derived Z-scheme heterojunctions. This study provides an experimental basis for amplifying the potential of sonosensitizers while optimizing SDT-mediated systemic immunity while avoiding interference caused by additional adjuvants.
Wanting Wang,Yuanting Wu,Long Chen,Chenggang Xu,Changqing Liu,Chengxin Li
Plasmonic effect-enhanced Z-type heterojunction photocatalysts comprise a promising solution to the two fundamental problems of current TiO2-based photocatalysis concerning low-charge carrier separation efficiency and low utilization of solar illumination. A plasmonic effect-enhanced TiN@anatase-TiO2/rutile-TiO2Z-type heterojunction photocatalyst with the strong interface of the N–O chemical bond was synthesized by hydrothermal oxidation of TiN. The prepared photocatalyst shows desirable visible light absorption and good visible-light-photocatalytic activity. The enhancement in photocatalytic activities contribute to the plasma resonance effect of TiN, the N–O bond-connected charge transfer channel at the TiO2/TiN heterointerface, and the synergistically Z-type charge transfer pathway between the anatase TiO2(A-TiO2) and rutile TiO2(R-TiO2). The optimization study shows that the catalyst with a weight ratio of A-TiO2/R-TiO2/TiN of approximately 15:1:1 achieved the best visible light photodegradation activity. This work demonstrates the effectiveness of fabricating plasmonic effect-enhanced Z-type heterostructure semiconductor photocatalysts with enhanced visible-light-photocatalytic activities.
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