Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.

Electronic waste produced by plastic, toxic, and semiconducting components of existing electronic devices is dramatically increasing environmental pollution. To overcome these issues, the use of eco-friendly materials for designing such devices is attaining much attention. This current work presents a recycled material-based triboelectric nanogenerator (TENG) made of plastic waste and carbon-coated paper wipes ([email protected]), in which the PWs are also collected from a waste bin. The resultant [email protected] TENG is then used for powering low-power electronic devices and, later, to generate a Morse code from a wearable for autonomous communication. In this application, the end users decode the Morse code from a customized LabVIEW program and read the transmitted signal. With further redesigning, a 9-segment keyboard is developed using nine-TENGs, connected to an Arduino controller to display the 9-segment actuation on a computer screen. Based on the above analysis, our [email protected] device is expected to have an impact on future self-powered sensors and internet of things systems.

The triboelectric effect is one of the most trending effects in energy harvesting technologies, which use one of the most common effects in daily life. Herein, an impervious silicone elastomer-based triboelectric nanogenerator (SE-TENG) is reported with a micro roughness-created silicone elastomer film and Ni foam as triboelectric layers with opposite surface charges. The surface roughness modification process was performed via a cost-effective soft lithography technique using sandpaper. The replicated film was then used as the negative triboelectric layer and porous Ni foam was used as the positive triboelectric layer. The device exhibited the advantage of high stability due to the porous nature of the Ni foam, which could not damage the roughness pattern of the elastomer film. The device generated a maximum electrical output of ∼370 V/6.1 μA with a maximum area power density of ∼17 mW m⁻² at a load resistance of 1 GΩ. Furthermore, the SE-TENG device was packed using polyethylene to protect it from humidity and made to be a water-resistant SE-TENG (WR-SE-TENG). The device was stable under different percentages of relative humidity, showing a uniform electrical output in the range of 10% RH to 99% RH. This proves that the packing is highly resistant against moisture and humidity. The device was also used for demonstrating its capability in powering small electronic components such as charging commercial capacitors, glowing LEDs and powering wrist watches. Further, the WR-SE-TENG device was used to scavenge bio-mechanical energy from human motions and also used for a real-time application of zero power consuming/self-powered pressure sensors. As an active sensor, the device showed linear sensing behavior and a sensitivity of 0.492 μA kPa⁻¹.