Ionic Liquids‐Based Iron Phosphide/Carbon Nanotubes Composites: High Active Electrocatalysts towards Hydrogen Evolution Reaction

Abstract

New catalyst for hydrogen generation by water electrolysis in aqueous acid is made by mixing N,N‐bis(4‐ (methoxycarbonyl)benzyl)‐N‐methyl‐d‐glucaminium bromide (MBMG−Br) and trichloroferrate (III) to form the iron containing ionic liquid (IL), MBMG‐FeCl3Br. This IL is mixed with carbon nanotubes (CNTs) and sodium hypophosphite (NaH2PO2) and then heated to 300 oC in an inert atmosphere to give the final catalyst, a CNT‐supported iron phosphide (FePMBMG/CNT), which exhibits catalytic activity toward hydrogen evolution reaction in 0.5 M aqueous sulfuric acid electrolyte with a low onset overpotential of 70 mV, a Tafel slope of 75.9 mV dec−1, 95% Faradaic efficiency (FE) and current densities of 10 and 20 mA cm−2, at overpotentials of 155 and 195 mV respectively, for a catalyst loading of 100 μg on 0.2 cm2 of glassy carbon electrode in which the IL to CNTs amount ratio is 1:1.

Ionic Liquids as Promisingly Multi-Functional Participants for Electrocatalyst of Water Splitting: A Review

“…ILs containing transition metal anions (such as FeCl 4 − , NiCl 3 − , and CoCl 3 − ) have been extensively studied [ 101 , 102 , 103 , 104 ]. This kind of ILs has the ability to provide metal elements for catalytic materials for water splitting [ 105 , 106 ]. A more ingenious design is to use metal anions and quaternary phosphonium salt cations to form ILs, such as [P 66614 ] 2 CoCl 4 [ 98 , 99 ], [P(C 6 H 13 ) 3 C 14 H 29 ]FeCl 4 [ 107 ], among others.…”

“…Fe 2 P/CNT exhibited excellent HER performance with current densities of 10 and 20 mA cm −2 at overpotentials of 115 and 150 mV, respectively. FeP(MBMG)/CNT, stemmed from [MBMG]FeCl 3 Br with CNTs and NaH 2 PO 2 [ 105 ], exhibited high activity for water splitting. This strategy can make not only the phosphorus and metal elements arrange according to the IL-induced structure but also evenly distribute and have many active sites.…”

Functions and performance of ionic liquids in enhancing electrocatalytic hydrogen evolution reactions: a comprehensive review

“…56–58 It is found that these ionic liquids could provide a kind of ion source for synthesis of catalytic materials for hydrogen evolution, which is also different from ionic liquids generally used as precursors. In 2017, Cui et al 59 reported the reaction of ionic liquid (MBMG-FeCl 3 Br) with carbon nanotubes (CNTs) and sodium hypophosphate (NaH 2 PO 2 ) to obtain CNT-supported iron phosphating (FeP MBMG /CNT) catalyst. It was found by comparative experiments that FeP (MBMG) /CNTs exhibited high activity among all synthesized catalysts.…”

Sustainable synthesis of supported metal nanocatalysts for electrochemical hydrogen evolution

“…In acidic conditions, FeP/CNT samples (typical SMNCs) synthesized via IL-assistance were the first to be employed as electrocatalysts for exploring their HER activity (Table 2) [156]. As the Fe atoms were highly dispersed in IL molecules, the produced metal NPs featured a small size and a good dispersion, which ensures an abundance of accessible active sites.…”