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The MXene combining high surface area, prominent biocompatibility, and wide near infrared (NIR) absorption has been recognized as one of the most promising materials for tumor therapy. The application of MXene in tumor therapy is negatively affected by the current design methods lack the control of size distribution and the great tendency to agglomerate as well as poor photodynamic therapy. To solve the above problems, we report a facile strategy to process Ti3C2 nanosheets into three-dimensional (3D) structure with honeycomb structure and anti-aggregation properties for synergistic therapy of chemotherapy, photothermal and photodynamic therapy. The 3D MXene is synthesized by spray drying, in which the MXene surface is oxidized to TiO2. The microspheres present prominent NIR light trigger photothermal effect and excellent NIR light photostability, which respond in an on–off manner. Moreover, the microspheres exhibit outstanding drug-loading capability of doxorubicin (DOX) as high as 87.3%, and substantial singlet oxygen generation (1O2) was shown under 808 nm laser and UV light irradiation. Our studies indicate that 3D MXene-DOX could effectively achieve Hela cells killing in vitro, which provides a multifunctional drug delivery platform as a prospective candidate for future combined cancer therapy.

Advanced design and fabrication of high performance sulfur cathodes with improved conductivity and chemical adsorption towards lithium polysulfides (LiPS) are crucial for further development of Li–S batteries. Hence, we designed a TiO2/Co3O4-CNTs composite derived from Ti-MOF (MIL-125) as the host matrix for sulfur cathode. The polar nature of metal oxides (TiO2, Co3O4) creates the adsorptive sites in the composite and leads to an efficient chemical capture of LiPS. The CNTs ensure the contact between S/Li2S and the host material with high conductivity, enhanced charge transfer and fast electrochemical kinetics. At the same time, the CNTs strengthen the stability of the electrode material. Consequently, the as-prepared TiO2/Co3O4-CNTs composite showed excellent electrochemical performance. The cell with S–TiO2/Co3O4-CNTs delivers an initial specific capacity of 1270 mAh g–1 at 0.2 C and high rate performance with a capacity of 603 mAh g–1 at 3 C.

Lithium-sulfur (Li/S) batteries are promising portable energy storage devices if the defects of insufficient conductivity and obvious shuttle effect can be effectively suppressed. In this work, a unique caddice-like ball carbon nanotubes/CoO (CNTs/CoO) microspheres have been synthesized through a facile spray drying and following calcination method. By using cobalt acetate (Co(CHCOO)2) as a cobalt source, polymethyl methacrylate (PMMA) as a pore former and CNTs as the supporting frame, the as-prepared CNTs/CoO microspheres endowed with enriched interconnected pores and abundant scattered CoO nanoparticles on CNT walls. CNTs provided physical adsorption platforms for adsorption of polysulfides while ensuring the conductivity of the overall material. Polycrystalline CoO nanoparticles are uniformly deposited on CNT walls, providing additional confinement of polysulfides by strong chemical adsorption. In addition, the different content of CoO in the microspheres was regulated by the amount of added cobalt source during the preparation process. With both physical entrapment by CNTs and strong chemical interaction with CoO nanocrystals, this unique design can effectively promote the active material utilization and inhibit the shuttle effect. When employed as the sulfur host, an excellent electrochemical performance was achieved on the resulting sulfur-impregnated CNTs/CoO (S-CNTs/CoO) composite with the sulfur content of 73.0%. The obtained S-CNTs/CoO microspheres delivered an exceptional initial discharge capacity of 1340 mAh g-1 and a prominent cycling stability of 1116 mAh g-1 after 100 cycles at 0.2 C, as well as a superb rate capability of 600 mAh g-1 and 506 mAh g-1 at 2.0 C and 3.0 C, respectively. The results revealed that the S-CNTs/CoO composite was an enviable cathode material and showed an excellent potentiality in the application of Li/S batteries.

A three-dimensionally (3D) ordered macro-/mesoporous TiO2 (3DOM-mTiO2) was synthesized via a simple solvothermal process. 3DOM-mTiO2 was used as a sulfur carrier for cathode materials in a lithium-sulfur (Li-S) battery. The orderly interconnected macro and mesopores structure within the macropore walls yield a large pore volume and high specific surface area in 3DOM-mTiO2, which improved the sulfur loading capacity of the material. The S/TiO2 composite was synthesized as a cathode material for lithium/sulfur battery, which initially produced a high capacity of 1089 mAh g-1 and retained a value of 703 mAh g-1 after 200 cycles. An initial current rate of 0.2 C was used, which was further increased up to 2.5 C when a reversible capacity of 651 mAh g-1 was obtained. The excellent electrochemical performance can be attributed to the 3D ordered macro-/mesoporous structure of TiO2, which physically confines the soluble lithium polysulfides and diminishes the sulfur volume expansion upon cycling. In addition, the strong electrostatic attraction between the Ti-O bond and polysulfide stimulates the performance via stronger adsorption of the electrochemical reaction products.

We report the first demonstration of a high-efficiency photoelectrochemical (PEC) water splitting reaction using a novel Si NWs/WO3 core/shell photoanode prepared by a mild and inexpensive metal-catalyzed electroless etching process followed by dip-coating, airing and annealing methods. The dense and vertically aligned Si NWs/WO3 core/shell nanostructure were characterized by scanning electron microscopy, transmission electron microscopy and x-ray diffraction. In comparison to planar n-Si, Si NWs and planar Si/WO3, the Si NWs/WO3 samples showed significantly enhanced photocurrent over the entire potential sweep range. More significantly, the Si NWs/WO3 samples have an exceptionally low photocurrent onset potential of -0.6393 V versus reversible hydrogen electrode (RHE), indicating very efficient charge separation and charge transportation processes. The as-prepared electrode also has a photocurrent density of 2.7 mA cm-2 at 0.6107 V versus RHE in 0.5 M Na2SO4 solution under simulated solar light irradiation (100 mW cm-2 from 300 W Xenon lamp coupled with an AM 1.5 G filter). An optimal solar-to-hydrogen efficiency of about 1.9% was achieved at 0.2676 V versus RHE. Electrochemical impedance spectroscopy was conducted to investigate the properties of the charge transfer process, and the results indicated that the enhanced PEC performance may due to the increased charge separation. The x-ray photoelectron spectroscopy measurements indicated the chemical composition of the Si NWs/WO3 nanostructure. Our work has provided an efficient strategy to improve the energy conversion efficiency and photocurrent of water splitting materials.