Rational Functionalization Towards Redox‐Active TEMPO Stable Free‐Radical‐Hydrochar Composites

Abstract

Although both stable free organic radicals and biomass-derived hydrochars have emerged as appealing, green, multifunctional materials, their association has not been explored. In this study, strength is found to lie in their union, which primarily leads to stable redox-active free-radical-hydrochar composites that can generate unexpected opportunities for the development of advanced metal-free sustainable materials. The composites are obtained by a straightforward green one-pot hydrothermal procedure. The loading of stable free radicals of nitroxide type and their localization is engineered by the nature of the carbohydrate and the reaction status; vigorous reaction parameters promote faster nucleation and growth kinetics of the hydrochar products, leading to a covalent immobilization of redox species on the surface of the carbonaceous microspherical aggregates. The nitroxide free-radical-hydrochar materials demonstrate enhancements in terms of both electrocatalytic activity and capacitive features.

Redox-Active Nitroxide Radicals Grafted onto MXene: Boosting Energy Storage via Improved Charge Transfer and Surface Capacitance

“…Prominent EPR signal peaks appear in the spectrum of the T-Ti 3 C 2 T x film, which is absent from that of the pristine Ti 3 C 2 T x film, indicating the existence of a paramagnetic free radical on the T-Ti 3 C 2 T x film. Besides, the EPR signals of the T-Ti 3 C 2 T x film could be divided into triple signal lines due to the hyperfine structure of nitroxide radicals . The property of the magnetic particle could be determined by measuring the g factor through eq , which reflects the spin–orbital interaction of the electron in the paramagnetic molecules , g = h v β H where h is Planck’s constant, v is the microwave frequency, β is the Bohr magneton, and H is the resonance field, respectively.…”

“…Besides, the EPR signals of the T-Ti 3 C 2 T x film could be divided into triple signal lines due to the hyperfine structure of nitroxide radicals. 36 The property of the magnetic particle could be determined by measuring the g factor through eq 1, which reflects the spin−orbital interaction of the electron in the paramagnetic molecules 37,38 g hv H = (1) where h is Planck's constant, v is the microwave frequency, β is the Bohr magneton, and H is the resonance field, respectively. The calculated g-factor value of the T-Ti 3 C 2 T x film is 2.0017, which is consistent with the g-factor value of nitroxide radicals.…”