Synthesis, Fabrication, and Characterization of Nanostructures from Spent Reforming Catalysts

Abstract

It is extremely prudent and highly challenging to design an economical bifunctional electrocatalyst with effective electrocatalytic activity and high stability catalyst for electrochemical water splitting. As hundred tons of catalyst is annually deactivated by coking, so herein, we came up with a strategy to utilize spent methane reforming catalysts that were deactivated by formation of graphitic and fibrous carbon. An electrocatalyst of noble-metal free MoS2 and spent catalysts was successfully synthesized using cost effective and environmentally friendly hydrothermal method, which showed an exceptional performance towards hydrogen evolution reaction (HER) as well as oxygen evolution reaction (OER). At 25 mA cm−2 a phenomenal OER overpotential (η25) of 128 mV and 154 mV, while a modest HER η25 of 186 mV and 207 mV for respectively was resulted for MoS2@CNF and MoS2@GC, respectively. Furthermore, the synthesized catalysts exhibited a good long-term durability for about 18 hrs. at 100 µA cm−2 with unnoticeable change in HER LSV curve after 1000 cycles. This work of synthesizing an enhanced electrocatalyst from spent catalysts (highly conductive due to carbon) with minimal usage of an expensive MoS2 (having good electrocatalytic activity) gives a rationale to utilize coked catalysts for obtaining an enhanced electrocatalyst for overall water splitting. Keywords: spent methane reforming catalyst, noble-metal free molybdenum sulphides, electrocatalyst, hydrogen evolution reaction, oxygen evolution reaction