Utilizing mechanical energy to produce hydrogen is emerging as a promising way to generate renewable energy, but is challenged by low efficiency and scanty cognition. In this work, graphitic carbon nitride (g‐C3N4) with an atomically thin sheet‐like structure is applied for prominent piezocatalytic and photo‐enhanced piezocatalytic H2 production. It is revealed that the anomalous piezoelectricity in g‐C3N4 originates from the strong in‐plane polarization along the a‐axis, contributed by the superimposed polar tri‐s‐triazine units and flexoelectric effect derived from the structured triangular cavities, which provides powerful electrochemical driving force for the water reduction reaction. Furthermore, the photo‐enhanced charge transfer enables g‐C3N4 nanosheets to reserve more energized polarization charges to fully participate in the reaction at the surface reactive sites enriched by strain‐induced carbon vacancies. Without any cocatalysts, an exceptional photo‐piezocatalytic H2 evolution rate of 12.16 mmol g−1 h−1 is delivered by the g‐C3N4 nanosheets, far exceeding that of previously reported piezocatalysts and g‐C3N4 photocatalysts. Further, high pure‐water‐splitting performance with production of the value‐added oxidation product H2O2 via photo‐piezocatalysis is also disclosed. This work not only exposes the potential of g‐C3N4 as a piezo‐semiconductor for catalytic H2 evolution, but also breaks a new ground for the conversion of solar and mechanical energy by photomediated piezocatalytic reaction.

Photocatalytic CO2 reduction attracts substantial interests for the production of chemical fuels via solar energy conversion, but the activity, stability, and selectivity of products were severely determined by the efficiencies of light harvesting, charge migration, and surface reactions. Structural engineering is a promising tactic to address the aforementioned crucial factors for boosting CO2 photoreduction. Herein, a timely and comprehensive review focusing on the recent advances in photocatalytic CO2 conversion based on the design strategies over nano‐/microstructure, crystalline and band structure, surface structure and interface structure is provided, which covers both the thermodynamic and kinetic challenges in CO2 photoreduction process. The key parameters essential for tailoring the size, morphology, porosity, bandgap, surface, or interfacial properties of photocatalysts are emphasized toward the efficient and selective conversion of CO2 into valuable chemicals. New trends and strategies in the structural design to meet the demands for prominent CO2 photoreduction activity are also introduced. It is expected to furnish a comprehensive guideline for inside‐and‐out design of state‐of‐the‐art photocatalysts with well‐defined structures for CO2 conversion.

Summary: The development of a novel technique for the preparation of homogeneous BaTiO3/polyvinylidene fluoride (BT/PVDF) nanocomposites without obvious agglomeration of BaTiO3 particles was reported in this communication. The morphology, structure, and frequency dependence of the dielectric properties of the nanocomposites were characterized. All results show that the dielectric properties of the nanocomposites in this study are desirable, and the process for preparing the nanocomposites has potential applications in the electronic industry.TEM micrograph of dry BT/PVDF mixtures with nanosized BT particles.magnified imageTEM micrograph of dry BT/PVDF mixtures with nanosized BT particles.

Different samples of gadolinium (Gd)-doped Bi2WO6 were obtained by hydrothermal means, and their photocatalytic activities for degradation of rhodamine B (RhB) under visible-light irradiation were researched. The successful incorporation of Gd3+ ions into Bi2WO6 was detected by XRD and XPS, and the prepared samples have also been characteriazed by SEM, TEM, HRTEM, DRS, and PL. The results suggested that Gd doping has great influences on the visible-light photocatalytic activity as well as the microstructure. Appropriate doping content greatly improve photocatalytic activity due to the electron shallow-trapping mechanism for the efficient separation of electron and hole pairs, and the 1% Gd–Bi2WO6 sample with flower-like structure exhibited the highest photocatalytic activity. It has already been confirmed by photocurrent generation and electrochemical impedance spectra. The present research provides a simple and valid method for improving the visible-light-responding photocatalytic activity and fabricating hierarchical architectures of Bi2WO6.

Polymer-semiconductor PVDF∕LNO (polyvinylidene fluoride∕Li doped NiO) composites were fabricated via simple blending and hot-molding technique. The dielectric behavior of such composites was studied over broad frequency. The results revealed the dependence of percolation threshold on the conductivity of LNO filler in the composites. And the conductivity of the LNO fillers played an important role on the dielectric properties and critical exponents of the PVDF∕LNO composites. High dielectric constants and low conductivities of the composites were observed near the percolation threshold. Finally, critical exponents were also used to explain the experimental results, and provided useful information for understanding the resultant dielectric properties.

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One of the major challenges associated with fuel cells is exploring highly efficient and low-cost electrocatalysts for the oxygen reduction reaction (ORR). Herein, the feasibility of using Ti 3 C 2 MXene nanoparticles (NPs) to enhance the electrocatalytic activity of g-C 3 N 4 for ORR was investigated. By varying the content of Ti 3 C 2 NPs, a series of g-C 3 N 4 /Ti 3 C 2 heterostructures were obtained, displaying enhanced electrocatalytic activity, including a positive shift in both onset and peak potentials toward ORR, compared to the original g-C 3 N 4 in basic solution. We attribute the improvement to the favorable electrical conductivity of welldispersed Ti 3 C 2 MXene nanoparticles and also enhanced O 2 adsorption due to the electronic coupling effect between g-C 3 N 4 and Ti 3 C 2 in the heterostructures. This work demonstrates the potential of earth-abundant MXene family materials to construct low-cost and high-performance electrocatalysts.