Author(s): Belhaj, Ines ; Becker, J. Alexander ; Viana, Alexandre M. ; Gusmão, Filipe M.B. ; Chaves, Miguel ; Pereira, Eulália ; Šljukić, Biljana ; Balula, Salete S. ; Cunha-Silva, Luís ; Santos, Diogo M.F.
Date: 2026
Persistent ID: http://hdl.handle.net/10362/206522
Origin: Repositório Institucional da UNL
Subject(s): borohydride oxidation reaction; Direct borohydride fuel cell; Gold; Metal-organic framework; Analytical Chemistry; General Chemical Engineering; Electrochemistry
The highly stable metal-organic framework (MOF) composed of [Zr6O4(μ3-OH)4(OH)6(H2O)6(BTC)2]·nH2O units (MOF-808) was modified by incorporating gold (Au) nanoparticles and functional groups to enhance electrocatalytic activity for the borohydride oxidation reaction (BOR). Three composite materials (Au@MOF-808, Au@MOF-808-NH2, and Au@MOF-808-SH) were prepared by the incorporation of Au in structurally related MOFs, MOF-808, MOF-808-NH2, and MOF-808-SH, respectively. These composite materials were evaluated as anodic electrocatalysts for BOR in alkaline media using cyclic voltammetry and chronoamperometry. Among the prepared materials, Au@MOF-808-NH2 exhibited the highest BOR activity, with an apparent activation energy of 15.3 kJ mol−1, a reaction order of 0.6, an anodic charge transfer coefficient of 0.63, and a number of exchanged electrons of 4.4. The latter was significantly below the theoretical eight-electron value, indicating the presence of alternative reaction pathways. Notably, this material achieved a high mass-specific BOR peak current of 4.23 A μgAu−1, demonstrating outstanding electrocatalytic efficiency despite the ultralow noble metal loading. These results underscore the potential of Au@MOF-808-NH2 as a cost-effective and scalable anodic electrocatalyst for high-performance direct borohydride fuel cells.
