Pedro de Oliveira

As the world faces an escalating energy crisis, the necessity of adopting alternative energy sources becomes increasingly evident. Despite challenges, the imperative to prioritise these eco‐friendly alternatives remains paramount in paving the way for a more sustainable and resilient future for our planet and its inhabitants. The pursuit of sustainable energy sources has brought the oxygen reduction reaction (ORR) into the spotlight as a crucial cathodic reaction in energy‐converting systems, notably fuel cells (FCs). These FCs hold tremendous promise in providing an eco‐friendly and efficient energy supply. However, the widespread implementation of FCs is hindered by their reliance on expensive and scarce noble metal catalysts, such as platinum (Pt), which pose economic and environmental challenges. Hence, this work reports the preparation, characterisation (FTIR, XPS, SEM and EDX) and application of four composites based on doped‐carbon materials (CM) and on the Wells‐Dawson POM salt K 6 ⋅α‐[P 2 W 12 Mo 6 O 62 ] ⋅ 19H 2 O (P 2 W 12 Mo 6 @MWCNT_N8, P 2 W 12 Mo 6 @MWCNT_N6, P 2 W 12 Mo 6 @MWCNT_S6, and P 2 W 12 Mo 6 @GF_S6) as ORR electrocatalysts in alkaline medium (pH=13). The successful doping of the carbon materials with nitrogen (N) and sulphur (S) and the incorporation of the polyoxometalate were verified through comprehensive structural characterisation. Overall, P 2 W 12 Mo 6 @MWCNT_N8 exhibited favourable onset potentials of 0.84 V vs. RHE, highlighting its high catalytic activity. Additionally, the catalyst showed excellent tolerance to methanol crossover, retaining 91 % of initial current, which is crucial for practical fuel cell applications. Furthermore, the P 2 W 12 Mo 6 @MWCNT_N8 catalyst showed commendable stability, retaining 81 % of its initial current after 36000 seconds at an operating potential of E =0.46 V vs. RHE. These encouraging results denote the significant potential of this electrocatalyst in advancing sustainable energy conversion technologies.