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We have successfully prepared a three-dimensional vanadoborate (VBO) with a lantern-type [V6B20] cluster by solvothermal method with the molecular formula of [EtNH3]2[1,3-diapH2]2H2[V6B20O50H8]·4H2O (EtNH2 = ethylamine; 1,3-diap = 1,3-diaminopropane) (VB-1). The title complex represents a novel example of a VBO introducing two different organic amines (EtNH2 and 1,3-diap) into the framework, which interact with the host framework and guest water molecules via N–H⋯O, O–H⋯O bonds, constructing a complex hydrogen-bonding network system for proton transport. In this study, the obtained VB-1 exhibits structural insolubility and is employed as a proton-conductive additive to modify the Nafion matrix, enabling the preparation of a thermally and aqueously stable VB-1/Nafion composite at intermediate temperatures. The CV and AC impedance studies reveal a significant enhancement in the proton conductivity of Nafion doped with VB-1 compared to pure Nafion. Remarkably, the modified membrane displays a remarkable 17.8- and 11.9-fold enhancement in proton conductivity compared to the pristine membrane at temperatures of 293 K and 343 K, respectively, surpassing the vast majority of previously reported Nafion-based composite membranes that were modified with MOFs and POMs under identical testing conditions. This improvement can be attributed primarily to the reduction in ohmic resistance caused by the hygroscopic and insoluble VBO solid, which effectively retains water within its framework through hydrogen bonding with protons at elevated temperatures, thereby facilitating efficient proton transport across the membrane. The fuel cell performance of the MEA based on the VB-1/Nafion composite membrane exhibits a significant enhancement, resulting in a 28.3% increase in peak power density compared to pure Nafion at 80 °C under 100% RH. Our study represents pioneering utilization of VBOs as fillers for proton exchange membranes (PEMs), emphasizing the imperative need for further research endeavors in this field. These findings underscore the potential application of VBOs in technologically relevant embodiments for long-distance proton conductivity through composite membranes and demonstrate their promising prospects in PEM applications. [ABSTRACT FROM AUTHOR]

Low carrier separation efficiency and slow surface reaction kinetics are the main factors for restricting the development of photocatalytic technology. Construction of double Z - scheme heterojunction and deposition of cocatalyst on semiconductor are considered to be effective strategies to solve these problems. However, it is challenging to integrate dual Z-scheme heterojunction and cocatalyst in one system to enhance photocatalytic activity. In our paper, a novel ternary heterostructure TiO 2 /g-C 3 N 4 /NiCoP (TCNNCP) photocatalyst was constructed by depositing NiCoP cocatalyst on three-dimensional spherical TiO 2 /g-C 3 N 4 surface. NiCoP in the composite can not only promote the surface reaction kinetics by reducing overpotential as a cocatalyst, but also improve the photogenerated carrier separation efficiency by constructing double Z-scheme heterojunctions with TiO 2 and g-C 3 N 4 as semiconductors. As a result, the optimized TCNNCP-2 composite exhibited a significantly improved photocatalytic hydrogen production activity of 2305.5 μmol g−1, which was 20.21 times higher than that of pure TiO 2 and 3.10 times higher than that of binary TiO 2 /g-C 3 N 4 composite. Additionally, TCNNCP-2 demonstrated excellent photocatalytic activity with an 86.2% removal rate for Cr(VI) within 2 h. These outstanding results can be attributed to the synergistic effect achieved through the construction of double Z-scheme heterojunctions and loading NiCoP cocatalyst, which enhance light-harvesting capability, carrier separation and transmission efficiency while promoting surface photocatalytic reactions. This research will contribute to the development of more bifunctional noble metal-free cocatalysts for efficient photocatalysis. [Display omitted] • A novel TiO 2 /g-C 3 N 4 /NiCoP photocatalyst was fabricated by depositing NiCoP cocatalyst on the surface of TiO 2 /g-C 3 N 4. • The TiO 2 /g-C 3 N 4 /NiCoP composite exhibited excellent photocatalytic activity for H 2 evolution and Cr(VI) reduction. • Integration of dual Z-scheme heterojunction and cocatalyst in one system improves photocatalytic activity. • Photocatalytic mechanism and the role of NiCoP in TiO 2 /g-C 3 N 4 /NiCoP ternary heterojunction were investigated in detail. [ABSTRACT FROM AUTHOR]