Nanoengineering silicon materials by metal-assisted chemical etching for thermal energy harvesting

Low-thermal heat waste energy harvesting represents a transformative technology for powering wireless sensing networks and electronic devices, particularly in remote and challenging environments. This review comprehensively examines the utilization of nanoporous silicon materials for thermal energy harvesting applications, focusing on their fabrication through metal-assisted chemical etching (MACE) and their unique properties that enhance energy conversion efficiency. The high surface area-to-volume ratio of nanoporous silicon significantly improves heat interaction and thermal-to-electrical energy conversion. We analyze the material properties and fabrication methods of nanoporous silicon, providing detailed evaluation of its performance in thermal energy harvesting applications. Experimental data demonstrates that nanoporous silicon achieves thermoelectric figures of merit (ZT) comparable to traditional materials while offering environmental and economic advantages. The review presents two innovative approaches for thermoelectric generators: solid-state configurations and ionic liquid implementations. Through systematic material evaluation and application demonstrations, we establish nanoporous silicon as an efficient and environmentally friendly solution for thermal energy harvesting. Our findings indicate that nanoporous silicon not only addresses the limitations of conventional thermoelectric materials but also provides a scalable and sustainable approach for enhancing energy harvesting system performance. This research contributes to advancing sustainable energy technologies and improving the viability of wireless sensing networks across various environmental conditions.