To avoid interference from unexpected background noises and obtain high fidelity voice signal, acoustic sensors with high sensitivity, flat frequency response, and high signal-to-noise ratio (SNR) are urgently needed for voice recognition. Graphene-oxide (GO) has received extensive attention due to its advantages of controllable thickness and high fracture strength. However, low mechanical sensitivity (S_M) introduced by undesirable initial stress limits the performance of GO material in the field of voice recognition. To alleviate the aforementioned issue, GO diaphragm with annular corrugations is proposed. By means of the reusable copper mold machined by picosecond laser, the fabrication and transfer of corrugated GO diaphragm are realized, thus achieving a Fabry–Perot (F–P) acoustic sensor. Benefitting from the structural advantage of the corrugated GO diaphragm, our F–P acoustic sensor exhibits high S_M (43.70 nm/Pa@17 kHz), flat frequency response (−3.2 to 3.7 dB within 300–3500 Hz), and high SNR (76.66 dB@1 kHz). In addition, further acoustic measurements also demonstrate other merits, including an excellent frequency detection resolution (0.01 Hz) and high time stability (output relative variation less than 6.7% for 90 min). Given the merits presented before, the fabricated F–P acoustic sensor with corrugated GO diaphragm can serve as a high-fidelity platform for acoustic detection and voice recognition. In conjunction with the deep residual learning framework, high recognition accuracy of 98.4% is achieved by training and testing the data recorded by the fabricated F–P acoustic sensor.

Flexible graphite film (FGF), as a traditional interface heat dissipation material, has high anisotropy. It is a challenge to enhance both in-plane and through-plane thermal conductivity of FGF. For this reason, the effects of oxygen content, layer spacing, density and particle size on the in-plane and through-plane thermal conductivity of FGF were studied by both molecular simulation and experimental investigation. The simulation results indicate that the ways to improve the thermal conductivity of FGF include reducing oxygen content and layer spacing, increasing the density and matching the size of graphite sheets. The FGF prepared from room temperature exfoliated graphite (RTFGF) has a wide range of adjustable density (1.3–2.0 g/cm³) and thickness (50–400 μm). The thermal conductivity of the RTFGF is significantly improved after heat treatment owing to reduced oxygen content and layer spacing, which is consistent with the simulation results. Moreover, RTFGF with both high in-plane (518 W·m⁻¹·K⁻¹) and through-plane (7.2 W·m⁻¹·K⁻¹) thermal conductivity can be obtained by particle size matching of graphite.

Two-dimensional transition metal dichalcogenides (TMDCs) have been regarded as an intriguing platform for exploring novel physical phenomena and optoelectronic devices due to their excitonic emission characteristics derived from the atomic thin thickness and reduced dielectric screening effect. Notably, monolayer TMDCs with a direct bandgap exhibiting strong photoluminescence (PL) are promising candidates for the light-emitting devices, while the interlayer excitons in heterostructures hold great potential for the photonic chips and optical communication applications. However, the non-ideal photoluminescent intensity and quality due to the ultrathin thickness and high defect density of experimentally obtained monolayer TMDCs limit the further development for the light-emission applications. Here, we summarize the research progress on the PL manipulation of the excitonic emission in TMDCs, where the PL intensity enhancement and emission wavelength regulation are included. The concept and characteristics of excitons are overviewed firstly, followed by the discussion on the evaluation and characterization of excitonic emission. The state-of-the-art progress on the manipulation of the neutral excitons and interlayer excitons PL are then summarized. Finally, the challenges and prospects are proposed.

Understanding the substrate and temperature effect on thermal transport properties of transition metal dichalcogenides (TMDs) monolayers are crucial for their future applications. Herein, a dual-wavelength flash Raman (DF-Raman) method is used to measure the thermal conductivity of monolayer WS₂ at a temperature range of 200–400 K. High measurement accuracy can be guaranteed in this method since the influence of both the laser absorption coefficient and temperature-Raman coefficient can be eliminated through normalization. The room-temperature thermal conductivity of suspended and supported WS₂ are 28.5 ± 2.1 (30.3 ± 2.0) and 15.4 ± 1.9 (16.9 ± 2.1) W/(m·K), respectively, with a ~ 50% reduction due to substrate effect. Molecular dynamics (MD) simulations reveal that the suppression of acoustic phonons is mainly responsible for the striking reduction. The behaviors of optical phonons are also unambiguously investigated using Raman spectroscopy, and the in-plane optical mode, E ${}_{2\mathrm{g}}^1$(Γ), is surprisingly found to be slightly enhanced while out-of-plane mode, A_1g(Γ), is suppressed due to substrate interaction, mutually verified with MD results. Our study provides a solid understanding of the phonon transport behavior of WS₂ with substrate interaction, which provides guidance for TMDs-based nanodevices.

Sodium ion hybrid capacitors (SIHCs) are regarded as advanced power supply systems. Nevertheless, the kinetics imbalance of cathode and anode suppresses the further performance improvement of SIHCs. The carbonaceous anode materials are promising and many strategies have been utilized to increase the capacity of sloping region or accelerate the reaction rate of plateau region. However, it is still challenging to simultaneously realize high mesopore/micropore volume ratio, large interlayer distance (> 0.37 nm), and abundant and favorable heteroatoms-doping by a simple method. Herein, we report N, P, O ternary-doped mesoporous carbon (PNPOC-T, T = 700, 800 or 900) with large interlayer distance (~0.4 nm) as anode materials. The PNPOC-T were prepared by a simple in-situ polymerization of aniline and phytic acid on the exfoliated graphitic nitrogen carbide (g-C₃N₄) and subsequent carbonization. The obtained PNPOC-800 exhibits an excellent rate performance (101.5 mA·h·g⁻¹ at 20 A·g⁻¹), which can be attributed to the high surface-controlled capacitive behavior ratio and rapid ion diffusion. The optimum SIHCs display a high energy density of 105.48 W·h·kg⁻¹ and a high power density of 13.59 kW·kg⁻¹. Furthermore, the capacitance retention rate of SIHCs can reach 87.43% after 9 000 cycles at 1 A·g⁻¹.