Pt decorated Artocarpus heterophyllus seed derived carbon as an anode catalyst for DMFC application

Abstract

A carbohydrate rich Artocarpus heterophyllus seed (AHS) is processed via a hydrothermal carbonization method (HTC) for various reaction times (12, 18, 24 and 30 h) and further thermally carbonized at 700 °C under N₂ atmosphere to sequester a high surface area carbon. Subsequently, Pt NPs are also decorated on the prepared carbon and this was used as an anode catalyst for a methanol oxidation reaction (MOR). The XRD and Raman spectra showed the as-synthesized material has a typical graphitic structure of carbon and an fcc structure of platinum with a grain size smaller than 3–4 nm. The presence of functional groups including –OH, –CO and –C–O are identified along with some heteroatoms on the surface of carbon through Fourier transform infrared (FT-IR) spectroscopy. X-ray photoelectron spectroscopy analysis exposed the presence of expected species such as C 1s, O 1s, N 1s and Pt 4f. Moreover, BET analysis of the spherical hydrochar carbonized at 700 °C showed a surface area of 431.5 m² g⁻¹ with a mean pore diameter of 3.2 nm and a pore volume of 0.354 cm³ g⁻¹. Morphological analysis such as Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) images revealed the spherical nature of the obtained hydrochar as well as its transformation into an agglomerated network after carbonization at 700 °C. The obtained Pt loaded carbon showed an excellent electrocatalytic activity in the potential range of interest with a high ECSA of 261.4 m² g⁻¹ for Pt/C (hydrochar formed during 24 h and carbonized at 700 °C). Moreover, the Pt decorated optimized carbon sample has much higher peak current and mass activity of about 0.32 mA mg⁻¹ and 54.4 A g⁻¹ towards MOR. In addition, chronoamperometry analysis also exposed a good stability over 10 000 s. It is also legitimated that a 20 : 80 wt% of Pt/C loading shows a high current density with no relevant change in the onset potential and long-term stability during MOR with a few comparable results.