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[Display omitted] • Cu2+-chelated SPEEK membrane with high IEC is prepared. • High mechanical and dimensional stability are observed for SPEEK-Cu membrane. • Proton conductivity of SPEEK-based membranes reaches 0.074 S/cm at −25 °C. • Water states of samples at subzero temperatures are quantified via DSC analysis. • SPEEK-Cu membrane possesses a stronger anti-freezing property. Improving the proton conductivity (σ) of proton exchange membranes at low temperatures is very important for expanding their application areas. Here, sulfonated poly ether ether ketone (SPEEK) membranes were prepared with different sulfonation degrees, and its maximum ion exchange capacity is 3.15 mmol/g for 10 h at 60 °C. Highly sulfonated SPEEK membrane exhibits ultra-high water uptake and excellent proton conductivity of 0.074 S/cm at −25 °C due to its abundant −SO 3 H. Nevertheless, its high swelling ratio and low mechanical strength are not conducive to the practical application of the membrane. Luckily, by employing the chelation of Cu2+ with −SO 3 − on the SPEEK chain, Cu2+-coordinated SPEEK membranes were prepared, and they not only retain high −SO 3 H content but also possess robust mechanical properties and good dimensional stability compared to pristine SPEEK membrane. Meanwhile, the σ of the SPEEK-Cu membrane reaches 0.054 S/cm at −25 °C, and its fuel cell maximum power (W max) reaches 0.42 W/cm2 at −10 °C, demonstrating superior low-temperature performance in comparison to other reported materials. Particularly, water states in the prepared membranes are quantified by low-temperature differential scanning calorimetry. Because much more water bound to the plentiful −SO 3 H and Cu2+ inside the membrane endows it with anti-freezing performance, the decay of the σ and the W max for the SPEEK-Cu membrane is retarded at sub-zero temperatures. It is envisioned that composite membranes comprising metal ions such as Cu2+-SPEEK have a high potential for sub-zero fuel cell applications. [ABSTRACT FROM AUTHOR]

[Display omitted] The exploration of highly efficient sunlight-assisted photocatalyst for photodegradation of organic contaminants or energy conversion is strongly encouraged. In this work, we designed a novel three-dimensional spindle-like Sv-ZIS@NMFe heterojunction made of amino functionalized NH 2 -MIL-88B(Fe) (NMFe) and ZnIn 2 S 4 nanosheets with abundant sulfur vacancies (Sv-ZIS). The structural properties of NMFe materials, such as a clearly defined system of pores and cavities, were retained by the Sv-ZIS@NMFe composites. Additionally, the incorporation of sulfur vacancies, –NH 2 functional groups, and well-matched energy level positions led to various synergistic effects that considerably enhanced internal electron transformation and migration, as well as improved adsorption performance. Consequently, under visible light irradiation, the optimized sample exhibited superior hydrogen production activity and tetracycline hydrochloride photodegradation performance. At last, density functional theory calculations was used to further elucidated the possible photoreactivity mechanism. This study demonstrates that the Sv-ZIS@NMFe heterojunction materials formed by ZnIn 2 S 4 with suitable sulfur vacancies and amino functionalized Fe-MOFs have promising applications in photocatalysis. [ABSTRACT FROM AUTHOR]

Se decorated CdS nanowires with few-layer MoSe 2 nanosheets are fabricated for efficient H 2 production. The piezoelectric field of MoSe 2 nanosheets promotes the separation of free charges. Compared with the photocatalysis, the piezo-photocatalysis yields a superior H 2 evolution rate of 59.1 mmol/h g−1 (124.9% that of photocatalysis). [Display omitted] The build-in electric field by the construction of heterojunction is one of the most promising strategies to suppress the recombination of photogenerated carriers. Here, we reported a piezo-photocatalytic system composed of Se-decorated CdS nanowires and few-layered edge-on MoSe 2 nanosheets for efficient H 2 generation by two-pot hydrothermal synthesis. The few-layered MoSe 2 exposed abundant edge sites for hydrogen evolution reaction (HER). The activity of 20-MoSe 2 /CdS 0.95 Se 0.05 (20-MS/CSS, with 20 mol% of MoSe 2 loading) nanocomposite casted a remarkable photocatalytic HER performance, with a rate of 47.3 mmol h−1 g−1. Moreover, MoSe 2 nanosheets deformed to generate the piezoelectric polarization field under magnetic stirring, which rendered efficient separation of photogenerated carriers, resulting in a piezo-photocatalytic synergistic effect. As a result, the HER of 20-MS/CSS at 900 rpm for piezo-photocatalysis was 59.1 mmol h−1 g−1, which was 1.25 times that of 20-MS/CSS for photocatalysis. Meanwhile, the photoelectrochemical measurements further visualized the piezo-photoelectric synergy. This study exposes a new way for utilizing mechanical energy to improve photocatalytic performance, and achieving high piezo-photocatalysis. [ABSTRACT FROM AUTHOR]

Few-layered MoSe 2 nanosheets were grown vertically on TiO 2 nanorods (TNr) to synthesis a direct Z-scheme heterojunction, exhibiting efficient piezocatalytic and piezo-photocatalytic performance. Moreover, a piezo-photoelectric synergistic effect of nanocomposites was also observed by current outputs. Our results highlight significance in the design of heterojunction for capturing fluid mechanical energy and improving piezo-photocatalytic synergistic effect. [Display omitted] Nano-semiconductor materials coupled with piezoelectric effect have received extensive attention due to their wide application in catalysis. In this work, few-layered MoSe 2 nanosheets were grown vertically on TiO 2 nanorods (TNr) to synthesize a direct Z-scheme heterojunction, exhibiting efficient piezocatalytic and piezo-photocatalytic performance. The MoSe 2 /TNr heterostructure exhibited superior piezoelectric degradation efficiency, successfully removing over 98% of RhB within 360 s under continuous magnetic stirring in dark. Compared with piezocatalysis, the piezo-photocatalytic system possessed higher degradation efficiency and cycle stability. Furthermore, a piezo-photoelectric synergistic effect of nanocomposites was observed by current outputs. Under stirring conditions, the current density of depleted MoSe 2 /TNr and MoSe 2 nanosheets were respectively 6.3 μA/cm2 and 5.5 μA/cm2. When light and stirring were applied, the MoSe 2 /TNr current density increased twice to 13.2 μA/cm2, while the MoSe 2 nanosheets didn't exhibit improvement. Through the direct Z-scheme heterojunction of MoSe 2 /TNr, photoexcitation and piezoelectric polarization work together to effectively replenish carriers under light irradiation, and then rapidly separate free charges through piezopotential. This work broadens the application prospects of piezocatalysis and piezo-photocatalysis in renewable energy harvesting and water purification. [ABSTRACT FROM AUTHOR]

[Display omitted] Piezocatalysis, driven by mechanical energy and piezoelectric effect, is of great potential in addressing the environmental issues. In this work, a piezoelectric catalyst was fabricated by growing few-layer MoS 2 nanosheets onto CuS, for the piezocatalytic degradation of Rhodamine B (RhB), methylene blue (MB) and hexavalent chromium (Cr (VI)). The excellent removal efficiency of Cr (VI) and RhB can be reached 100% within 180 s, through the piezocatalysis of CuS/MoS 2 -0.6 driven by mechanical stirring in the dark. Impressively, the piezoelectric current of CuS/MoS 2 -0.6 is 48 and 35.7 times higher than that of pure CuS and MoS 2 , respectively. The significantly enhanced piezocatalytic performance can be ascribed to the formation of CuS/MoS 2 heterojunction and the piezoelectric field generated by MoS 2 nanosheets, which promotes the efficient separation of electrons and holes. This study provides insights into strategies to improve catalytic performance through utilizing mechanical energy and opens a new horizon for environmental remediation. [ABSTRACT FROM AUTHOR]