Lignocellulosic Biomass for the Fabrication of Triboelectric Nano-Generators (TENGs)-A Review.

Growth in population and increased environmental awareness demand the emergence of new energy sources with low environmental impact. Lignocellulosic biomass is mainly composed of cellulose, lignin, and hemicellulose. These materials have been used in the energy industry for the production of biofuels as an eco-friendly alternative to fossil fuels. However, their use in the fabrication of small electronic devices is still under development. Lignocellulose-based triboelectric nanogenerators (LC-TENGs) have emerged as an eco-friendly alternative to conventional batteries, which are mainly composed of harmful and non-degradable materials. These LC-TENGs use lignocellulose-based components, which serve as electrodes or triboelectric active materials. These materials can be derived from bulk materials such as wood, seeds, or leaves, or they can be derived from waste materials from the timber industry, agriculture, or recycled urban materials. LC-TENG devices represent an eco-friendly, low-cost, and effective mechanism for harvesting environmental mechanical energy to generate electricity, enabling the development of self-powered devices and sensors. In this study, a comprehensive review of lignocellulosic-based materials was conducted to highlight their use as both electrodes and triboelectric active surfaces in the development of novel eco-friendly triboelectric nano-generators (LC-TENGs). The composition of lignocellulose and the classification and applications of LC-TENGs are discussed.

Online self-powered Cr(VI) monitoring with autochthonous Pseudomonas and a bio-inspired redox polymer.

The assessment of water quality is critical to implement preventive and emergency interventions aimed to limit/avoid environmental contamination and human exposure to toxic compounds. While established high-resolution techniques allow quantitative and qualitative determination of contaminants, their widespread application is not feasible due to cost, time, and need for trained personnel. In this context, the development of easy-to-implement approaches for preliminary detection of contaminants is of the utmost importance. Herein, a portable self-powered microbial electrochemical sensor enabling online monitoring of Cr(VI) is reported. The biosensor employs a bio-inspired redox mediating system to allow extracellular electron transfer between a bacterial isolate from chromium-contaminated environments and the electrode, providing a clear response to Cr(VI) presence. The biosensor shows good linearity (R2 = 0.983) and a limit of detection of 2.4 mg L-1 Cr(VI), with a sensitivity of 0.31 ± 0.02 µA cm-2 mgCr(VI)-1 L. The presented microbial bioanode architecture enhanced biosensor performance thanks to the improved "electrical wiring" between biological entities and the abiotic electrode surface. This approach could be easily implemented in engineered electrode surfaces, such as paper-based multi-anodes that maximize bacterial colonization, further improving biosensor response. Graphical abstract.

Plant Microbial Fuel Cells⁻Based Energy Harvester System for Self-powered IoT Applications.

The emergence of modern technologies, such as Wireless Sensor Networks (WSNs), the Internet-of-Things (IoT), and Machine-to-Machine (M2M) communications, involves the use of batteries, which pose a serious environmental risk, with billions of batteries disposed of every year. However, the combination of sensors and wireless communication devices is extremely power-hungry. Energy Harvesting (EH) is fundamental in enabling the use of low-power electronic devices that derive their energy from external sources, such as Microbial Fuel Cells (MFC), solar power, thermal and kinetic energy, among others. Plant Microbial Fuel Cell (PMFC) is a prominent clean energy source and a step towards the development of self-powered systems in indoor and outdoor environments. One of the main challenges with PMFCs is the dynamic power supply, dynamic charging rates and low-energy supply. In this paper, a PMFC-based energy harvester system is proposed for the implementation of autonomous self-powered sensor nodes with IoT and cloud-based service communication protocols. The PMFC design is specifically adapted with the proposed EH circuit for the implementation of IoT-WSN based applications. The PMFC-EH system has a maximum power point at 0.71 V, a current density of 5 mA cm - 2 , and a power density of 3.5 mW cm - 2 with a single plant. Considering a sensor node with a current consumption of 0.35 mA, the PMFC-EH green energy system allows a power autonomy for real-time data processing of IoT-based low-power WSN systems.