Reutilizing Methane Reforming Spent Catalysts as Efficient Overall Water -Splitting Electrocatalysts

It is extremely prudent and highly challenging to design a greener bifunctional electrocatalyst that shows effective electrocatalytic activity and high stability toward electrochemical water splitting. As several hundred tons of catalysts are annually deactivated by deposition of carbon, herein, we came up with a en strategy to reutilize spent methane reforming catalysts that were deactivated by the formation of graphitic carbon (GC) land carbon nanofibers (CNF). An electrocatalyst was successfully synthesized by in situ deposition of noble metal-free MoS2 over spent catalysts via a hydrothermal method that showed exceptional performance regarding the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). At l 25 mA cm -2, phenomenal OER overpotentials (r/25) of 128 and 154 mV land modest HER overpotentials of 186 and 207 mV were achieved for MoS2@CNF and MoS2@GC, respectively. Moreover, OER Tafel slopes of 41 and 71 mV dec-1 and HER Tafel slopes of 99 and 107 mV dec-1 were obtained for IVIoS,@CNF and MoS2@GC, respectively. Furthermore, the synthesized catalysts exhibited, good long-term durability for about 18 h at 100 pA cm-2 with unnoticeable changes in the linear sweep voltammetry (LSV) curve of the IHER after 1000 cycles. The carbon on the spent catalyst increased the conductivity, while IVIoS2 enhanced the electrocatalytic activity; hence, the synergistic effect of both materials resulted in enhanced electrocatalysts for overall water splitting. This work of synthesizing enhanced nanostructured electrocatalysts with minimal usage of inexpensive MoS, gives a rationale for engineering potent greener electrocatalysts.

Automated summary

A greener bifunctional electrocatalyst was successfully synthesized by in situ deposition of noble metal-free MoS2 over spent methane reforming catalysts, showing exceptional performance in hydrogen and oxygen evolution reactions. This catalyst exhibited low overpotentials for both reactions and good long-term durability, demonstrating the synergistic effect of carbon and MoS2 in enhancing electrocatalytic activity for water splitting.