New hollow nanotube structure designed to convert waste heat into electricity

Researchers at Pohang University of Science and Technology (POSTECH) in South Korea have developed a novel method to convert waste heat into electricity using hollow silicon nanotube structures. This advancement addresses the challenge of capturing waste heat from sources such as data centers, electric vehicle batteries, and industrial factories without relying on rare and costly materials.

The need for efficient waste heat recovery is growing as data centers and electric vehicles generate increasing amounts of heat. Traditional thermoelectric devices have been limited by the scarcity and expense of materials like bismuth and tellurium. Silicon, while abundant and suitable for mass production, has been ineffective as a thermoelectric material due to its high thermal conductivity.

The POSTECH team, led by Professor Chang-Ki Baek and Ph.D. candidate Ki Yeong Kim, has innovatively reduced silicon's thermal conductivity by transforming solid silicon nanowires into hollow nanotube structures. These hollow tubes decrease thermal conductivity by 70% compared to solid wires, even when both have the same surface area, resulting in a 33% cooler operation.

This reduction in thermal conductivity is attributed to phonon localization, where atomic vibrations that transfer heat become trapped in specific zones within the hollow nanotubes. Previously, achieving phonon localization required extreme conditions or complex materials, but the POSTECH team demonstrated it in a simple structure at near-room temperature.

The use of silicon, a common and inexpensive material, allows this technology to be easily integrated into existing semiconductor manufacturing processes. This compatibility could facilitate rapid commercialization, enhancing energy efficiency by converting waste heat into electricity and supporting a stable supply chain for thermal management solutions.