Advanced Cellulose-Nanocarbon Composite Films for High-Performance Triboelectric and Piezoelectric Nanogenerators

Multifunctional composite films with regenerated cellulose prepared via acid-catalytic degradation for in-situ growth of ZnO

Regenerated cellulose is extensively utilized as a natural polymer due to its actually natural piezoelectric properties as well as renewable properties, but suffers from processing difficulties and low piezoelectric constants (d33). Consequently, this work focuses on controlling the molecular weight of regenerated cellulose through pretreatment methods that promote the growth of in situ ZnO to enhance its d33. Firstly, the acid-catalyzed pulp fibers (PF) and zinc nitrate hexahydrate were added in NaOH/urea solvent to effectively prepare RC/ZnO composite film via regeneration and in-situ growth. The effects of the acid-catalytic degradation on the solubility of PF, the structure of RC, and the RC/ZnO composite film were systematically discussed. It is found that the hydrogen bond network structure in the RC/ZnO composite film prepared by 1.5 % ~ 6 h treated PF is the most regular, where the ZnO is well combined with substrate and dispersed evenly, and the d33 is up to 34.99 pm/V. Therefore, the maximum open-circuit voltage of the prepared piezoelectric generator (PEG) reaches 5 V. On this basis, a piezoelectric sensing system is developed, displaying portable and accurate detection performance to human movement. This work provides insights and ideas for the development and design of cellulose and ZnO composites.

Influence of MXene Composition on Triboelectricity of MXene-Alginate Nanocomposites

MXenes are highly versatile and conductive 2D materials that can significantly enhance the triboelectric properties of polymer nanocomposites. Despite the growing interest in the tunable chemistry of MXenes for energy applications, the effect of their chemical composition on triboelectric power generation has yet to be thoroughly studied. Here, we investigate the impact of the chemical composition of MXenes, specifically the Ti3CNTx carbonitride vs the most studied carbide, Ti3C2Tx, on their interactions with sodium alginate biopolymer and, ultimately, the performance of a triboelectric nanogenerator (TENG) device. Our results show that adding 2 wt % of Ti3CNTx to alginate produces a synergistic effect that generates a higher triboelectric output than the Ti3C2Tx system. Spectroscopic analyses suggest that a higher oxygen and fluorine content on the surface of Ti3CNTx enhances hydrogen bonding with the alginate matrix, thereby increasing the surface charge density of the alginate oxygen atoms. This was further supported by Kelvin probe force microscopy, which revealed a more negative surface potential on Ti3CNTx-alginate, facilitating high charge transfer between the TENG electrodes. The optimized Ti3CNTx-alginate nanogenerator delivered an output of 670 V, 15 μA, and 0.28 W/m2. Additionally, we demonstrate that plasma oxidation of the MXene surface further enhances triboelectric performance. Due to the diverse surface terminations of MXene, we show that Ti3CNTx-alginate can function as either tribopositive or tribonegative material, depending on the counter-contacting material. Our findings provide a deeper understanding of how MXene composition affects their interaction with biopolymers and resulting tunable triboelectrification behavior. This opens up new avenues for developing flexible and efficient MXene-based TENG devices.

Eco-friendly, compact, and cost-efficient triboelectric nanogenerator for renewable energy harvesting and smart motion sensing

In recent years, the growth of Internet of Things devices has increased the use of sustainable energy sources. An alternative technology is offered by triboelectric nanogenerators (TENGs) that can harvest green energy and convert it into electrical energy. Herein, we assessed three different nopal powder types that were used as triboelectric layers of eco-friendly and sustainable TENGs for renewable energy harvesting from environmental vibrations and powering electronic devices. These nanogenerators were fabricated using waste and recycled materials with a compact design for easy transportation and collocation on non-homogeneous surfaces of different vibration or motion sources. In addition, these TENGs have advantages such as high output performance, stable output voltage, lightweight, low-cost materials, and a simple fabrication process. These nanogenerators use the contact-separation mode between two triboelectric layers to convert the vibration energy into electrical energy. TENG with the best output performance is based on dehydrated nopal powder, generating an output power density of 2.145 mWm-2 with a load resistance of 39.97 MΩ under 3g acceleration and 25 Hz operating frequency. The proposed TENGs have stable output voltages during 22500 operating cycles. These nanogenerators can light 116 ultra-bright blue commercial LEDs and power a digital calculator. Also, the TENGs can be used as a chess clock connected to a mobile phone app for smart motion sensing. These nanogenerators can harvest renewable vibration energy and power electronic devices, sensors, and smart motion sensing.

A Recent Review of Electrospun Porous Carbon Nanofiber Mats for Energy Storage and Generation Applications

Electrospun porous carbon nanofiber mats have excellent properties, such as a large surface area, tunable porosity, and excellent electrical conductivity, and have attracted great attention in energy storage and power generation applications. Moreover, due to their exceptional properties, they can be used in dye-sensitized solar cells (DSSCs), membrane electrodes for fuel cells, catalytic applications such as oxygen reduction reactions (ORRs), hydrogen evolution reactions (HERs), and oxygen evolution reactions (OERs), and sensing applications such as biosensors, electrochemical sensors, and chemical sensors, providing a comprehensive insight into energy storage development and applications. This study focuses on the role of electrospun porous carbon nanofiber mats in improving energy storage and generation and contributes to a better understanding of the fabrication process of electrospun porous carbon nanofiber mats. In addition, a comprehensive review of various alternative preparation methods covering a wide range from natural polymers to synthetic carbon-rich materials is provided, along with insights into the current literature.