ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Novel pyrogallol/expanded graphite composites with multisource–triggered thermal energy conversion and storage at medium temperatures

Giang Tien Nguyen, Huynh Nguyen Anh Tuan, Nguyen Ngoc Que Anh, Ho Phuong, Nhung Thi Tran, Le Thi Duy Hanh, Minh Tam Le, and Dang Quang Hung

Faculty of Chemical and Food Technology, Ho Chi Minh City University of Technology and Engineering (HCMUTE), Ho Chi Minh City, Vietnam

E-mail: ntgiang@hcmute.edu.vn

Received: 28 December 2025  Accepted: 11 April 2026

Abstract:

In this work, pyrogallol (PYL) and expanded graphite (ExG) have been incorporated to form composite phase change materials (CPCMs) with varying PYL contents (60–90%) for multi–source triggered thermal energy conversion and storage at medium temperatures. ExG, with a suitable porous network, provided sufficient capillary and surface-tension forces to stabilize PYL in the CPCMs without leakage, even at PYL contents up to 80%. It was found that maintaining anhydrous PYL was key to achieving high thermal performance, as anhydrous PYL exhibited a thermal energy storage capacity up to 1.50 times that of hydrated PYL. The fabricated CPCM80 exhibited a high phase change enthalpy of 150.7 J/g at a phase change temperature of 127.3 ℃ and a suppressed supercooling degree by 23.0 ℃ compared to pure PYL. Its thermal conductivity was boosted to 14.1 times that of pure PYL, owing to ExG's high thermal conductivity. In addition, the high solar absorption and high electrical conductivity of ExG endowed the fabricated CPCMs with photothermal and electrothermal conversion and storage ability. In practice, the CPCM80 showed a high photothermal conversion efficiency of 72.6% under a solar simulator at 2000 W/m², and its electrothermal conversion could be triggered at an applied voltage as low as 2.0 V. The high thermal performance and good energy conversion abilities make the fabricated PYL/ExG CPCMs promising for thermal energy storage applications at medium temperatures.

Keywords: Pyrogallol; Expanded graphite; Medium–temperature heat storage; Photothermal conversion; Electrothermal conversion

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04908-0

Chemical Papers 80 (8) 8743–8755 (2026)