The supportless PtRh nanoclusters (Pt3Rh NC) were prepared using formic acid reductant. High-resolution transmission electron microscopy (HRTEM) showed individual particle sizes less than 7 nm, and energy-dispersive X-ray (EDX) analysis confirmed a 3:1 ratio of Pt and Rh. The as-prepared Pt3Rh NC exhibited an improved activity and durability toward electrocatalytic oxidation of methanol (MOR) and possesses greater CO tolerance than conventional PtRu and other Pt-based MOR catalysts. For comparison, the Vulcan carbon supported (Pt3Rh NC/VC) catalyst was prepared under identical conditions and used for MOR. The supportless Pt3Rh NC catalyst possessed mass activity of 1392.5 mA mg–1 with an I f/I b ratio of 2.61, which is nearly 3-fold higher than the Pt3Rh NC/VC and also comparable to the benchmark MOR catalysts. The surface poisoning rate was found to be relatively smaller compared to the standard PtRu/C catalysts (δ = 0.0044% s–1). The activation energy for MOR was found to be 22.5 kJ mol–1. The durability study for 4000 potential cycles in an acidic solution showed that nearly 78% of mass activity has been retained. The supportless Pt3Rh NC has much improved activity and stability compared to both Pt3Rh NC/VC and standard PtRu MOR catalysts. Therefore, the supportless Pt3Rh NC could be seen as a potential electrocatalyst for methanol oxidation due to high activity, enhanced stability, and diminished poisoning of the Pt surface, which is stabilized in the presence of Rh in nanocluster morphology.

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Spindle-shaped CeO 2 on bio-char carbon synthesized by in-situ hydrothermal method. Naturally occurring Spirulina platensis microalgae used as the carbon source. N, P -doped carbon and O-vacancy of Ce 3þ in CeO 2 /BC700 promote the ORR kinetics. CeO 2 /BC700 has good ORR activity and remarkable stability after 5000 cycles.

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