Atomically thin two-dimensional (2D) carbon nitride sheets (CNs) are attracting attention in the field of photocatalytic CO2 reduction. Because of the rapid recombination of photogenerated electron–hole pairs and limited more active sites, the photocatalytic efficiency of CNs cannot meet the actual requirements. Here, atomically thin 2D/2D van der Waals heterostructures of metal-free graphdiyne (GDY)/CNs are fabricated through a simple electrostatic self-assembly method. Experimental characterizations along with first-principles calculations show that the introduction of GDY in CNs promoted the transport of photogenerated carriers in the melon chain, thus suppressing the recombination of photogenerated electron–hole pairs. Both in situ FTIR measurements and DFT calculation confirm that the introduced GDY served as the CO2 adsorption site and enhanced the CO2 adsorption capacity of the CNs/GDY heterostructure. Thanks to the 2D/2D van der Waals heterojunction, the optimized CNs/GDY enhances significantly the CO generation rate up to 95.8 μmol g–1 that is 19.2-fold higher than that of CNs. This work provides a viable approach for the design of metal-free van der Waals heterostructure-based photocatalysts with high catalytic activity.

Monolayer molybdenum disulfide (MoS2) nanoenzymes exhibit a piezoelectric polarization, which generates reactive oxygen species to inactivate tumors under ultrasonic strain. However, its therapeutic efficiency is far away from satisfactory, due to stackable MoS2, quenching of piezo‐generated charges, and monotherapy. Herein, chitosan‐exfoliated monolayer MoS2 (Ch‐MS) is composited with atomic‐thin MXene, Ti3C2 (TC), to self‐assemble a multimodal nanoplatform, Ti3C2‐Chitosan‐MoS2 (TC@Ch‐MS), for tumor inactivation. TC@Ch‐MS not only inherits piezoelectricity from monolayer MoS2, but also maintains remarkable stability. Intrinsic metallic MXene combines with MoS2 to construct an interfacial Schottky heterojunction, facilitating the separation of electron–hole pairs and endowing TC@Ch‐MS increase‐sensitivity magnetic resonance imaging responding. Schottky interface also leads to peroxidase mimetics with excellent catalytic performance toward H2O2 in the tumor microenvironment under mechanical vibration. TC@Ch‐MS possesses the superior photothermal conversion efficiency than pristine TC under near‐infrared ray illumination, attributed to its enhanced interlaminar conductivity. Meanwhile, TC@Ch‐MS realizes optimized efficiency on tumor apoptosis with immunotherapy. Therefore, TC@Ch‐MS achieves an integrated diagnosis and multimodal treatment nanoplatform, whereas the toxicity to normal tissue cells is negligible. This work may shed fresh light on optimizing the piezoelectric materials in biological applications, and also give prominence to the significance of intrinsic metallicity in MXene.

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The high porosity, controllable size, high surface area, and chemical versatility of a metal-organic framework (MOF) enable it a good material for a triboelectric nanogenerator (TENG), and some MOFs have been incorporated in the fabrication of TENGs. However, the understanding of effects of MOFs on the energy conversion of a TENG is still lacking, which inhibits the improvement of the performance of MOF-based TENGs. Here, UiO-66-NH2 MOFs were found to significantly increase the power of a TENG and the mechanism was carefully examined. The electron-withdrawing ability of Zr-based UiO-66-family MOFs was enhanced by designing the amino functionalized 1,4-terephthalic acid (1,4-BDC) as ligand. The chemically modified UiO-66-NH2 was found to increase the surface roughness and surface potential of a composite film with MOFs embedded in polydimethylsiloxane (PDMS) matrix. Thus the total charges due to the contact electrification increased significantly. The composite-based TENG was found to be very durable and its output voltage and current were 4 times and 60 times higher than that of a PDMS-based TENG. This work revealed an effective strategy to design MOFs with excellent electron-withdrawing abilities for high-performance TENGs.

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