Development of gCN/Pt electrocatalysts for Vis-light-activated ethanol electrochemical valorization

In the search for renewable and sustainable energy resources, a promising fuel is biomass-derived ethanol (EtOH), whose low toxicity, easy handling, and high energy density (29.7 MJxkg^-1) have stimulated its valorization in direct ethanol fuel cells (DEFCs), with it eventually being photo-promoted for hydrogen generation [1,2]. Unfortunately, the most used DEFC anodic catalysts based on Pt suffer from high costs, supply shortages, and poor sustainability. In this regard, a key challenge is the reduction of platinum content, and maintaining at the same time an appreciable electrocatalyst activity that can be achieved through a modular dispersion of low-dimensional metal nanoaggregates onto suitable substrates.

In this context, the present work reports on the fabrication of heterocomposites based on platinum nanoparticles and graphitic carbon nitride (gCN), a metal-free Vis-light-active semiconductor (E_G=2.7 eV) endowed with the benefits of low cost, eco-friendly characteristics, and high structural and compositional flexibility. In fact, N-containing functional groups in gCN can effectively coordinate metal centers during the nucleation/growth of metal nanoparticles, allowing platinum content to be lowered and simultaneously boosting the system performance. The target materials are fabricated by an original route consisting of the electrophoretic deposition of exfoliated gCN on carbon paper, followed by the dispersion of Pt nanoparticles in ultra-low amounts (ca. μg/cm²) by sputtering from Ar plasmas. Optimization of processing conditions and the amount of deposited Pt yielded appreciable activity and stability towards ethanol oxidation in alkaline aqueous solutions, thanks to the synergistic Pt/gCN interactions. The obtained results highlight that attractive performances can be provided even by electrocatalysts containing very low platinum amounts, a key target that might pave the way to the implementation of photo-functional systems in the fields of chemical and solar energy conversion.

[1] D. Barreca et al., ChemSusChem, 17, e202401041 (2024).

[2] D. Barreca et al., Surf. Sci. Spectra, 31, 024002 (2024).