Dielectric materials, such as barium titanate (BT)-based materials, have excellent dielectric properties but require high temperatures (above 1300 °C) for ceramic fabrication, leading to high costs and energy loss. The cold sintering process (CSP) offers a solution to these issues and is gaining worldwide attention as an innovative fabrication route. In this work, we proposed an alternative organic ferroelectric phase, gamma-glycine (γ-GC), which acts as a transient liquid phase to fabricate high-density composites with barium titanate (BT) at low temperatures through CSP. Our findings show that the density of 15γ-GC/85BT reached 96.7%±1.6% when it was sintered at 120 °C for 6 h under 10 MPa uniaxial pressure. Scanning electron microscopy‒energy dispersive X-ray spectroscopy (SEM‒EDS) mappings of the composite suggested that γ-GC completely underwent the precipitation–dissolution process and, therefore, filled between BT particles. Moreover, X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the preservation of γ-GC without undesired phase transformation. In addition, the ferroelectric and dielectric properties of γ-GC/BT composites have been reported. The high dielectric constant (ε_r) was 3600, and the low dielectric loss (tanδ) was 1.20 at 200 °C and 100 kHz for the 15γ-GC/85BT composite. The hysteresis loop showed a remanent polarization (P_r) of 0.55 µC·cm⁻² and a coercive field (E_c) of 7.25 kV·cm⁻¹. Our findings reaffirmed that an organic ferroelectric material (γ-GC) can act as a transient liquid phase in a CSP that can successfully and sustainably fabricate γ-GC/BT composites at low temperatures while delivering outstandingly high performance.

Transparent, flexible, and high-performance triboelectric nanogenerator (TENG) from nature-derived materials are required for sustainable society development. However, low triboelectricity from natural material is generally observed. Tunable electronic band diagram (EBD) through facile manipulation is one of the efficient methods to promote the TENG output, requiring fundamental, in depth understanding. Herein, we employed the high quality, single crystal-like Ti₂NbO₇ nanosheets (NSs) with dual dielectric and semiconducting properties as filler for bacterial cellulose (BC)-based TENG. Several techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), ultraviolet–visible (UV–vis) absorption, energy dispersive X-ray spectroscopy (EDS), and synchrotron radiation X-ray tomographic microscopy (SRXTM) were applied to characterize the long-range structure, microstructure, optical properties, elemental composition, and three-dimensional (3D) distribution of components in the composites. The semi-transparent and flexible 5 vol.% Ti₂NbO₇ NSs/BC preserved the integrity of cellulose, contained well-dispersed nanosheets, reduced optical band gap (4.20 vs. 5.75 eV for BC), and increased surface roughness. The dielectric permittivity and conductivity increased with nanosheets content. Adding negatively-charged Ti₂NbO₇ NSs could regulate the charge affinity of BC composite via shifting of Fermi energy over that of Al. It is found that adding 5 vol.% NSs into the BC film improved electrical outputs (~ 36 V and ~ 8.8 μA), which are 2–4 times higher than that of pure BC, even when paired with Al which lies adjacent in triboelectric series. Our work demonstrated the method to enhance BC-based TENG performance through EBD regulation using multifunctional Ti₂NbO₇ NSs.