Highly Active and Stable Hybrid Catalyst of Cobalt-Doped FeS₂ Nanosheets–Carbon Nanotubes for Hydrogen Evolution Reaction

Abstract

Hydrogen evolution reaction (HER) from water through electrocatalysis using cost-effective materials to replace precious Pt catalysts holds great promise for clean energy technologies. In this work we developed a highly active and stable catalyst containing Co doped earth abundant iron pyrite FeS(2) nanosheets hybridized with carbon nanotubes (Fe(1-x)CoxS(2)/CNT hybrid catalysts) for HER in acidic solutions. The pyrite phase of Fe(1-x)CoxS(2)/CNT was characterized by powder X-ray diffraction and absorption spectroscopy. Electrochemical measurements showed a low overpotential of ∼0.12 V at 20 mA/cm(2), small Tafel slope of ∼46 mV/decade, and long-term durability over 40 h of HER operation using bulk quantities of Fe(0.9)Co(0.1)S(2)/CNT hybrid catalysts at high loadings (∼7 mg/cm(2)). Density functional theory calculation revealed that the origin of high catalytic activity stemmed from a large reduction of the kinetic energy barrier of H atom adsorption on FeS(2) surface upon Co doping in the iron pyrite structure. It is also found that the high HER catalytic activity of Fe(0.9)Co(0.1)S(2) hinges on the hybridization with CNTs to impart strong heteroatomic interactions between CNT and Fe(0.9)Co(0.1)S(2). This work produces the most active HER catalyst based on iron pyrite, suggesting a scalable, low cost, and highly efficient catalyst for hydrogen generation.

Ternary NiCoP nanosheet arrays: An excellent bifunctional catalyst for alkaline overall water splitting

“…S7 in the ESM), further indicating a faster electron transfer [34][35][36]. The outstanding HER activity of the ternary NiCoP NSA electrode can be attributed to the incorporation of metal atoms into binary metal phosphides, which may modify their electronic structure as well as tune the hydrogen adsorption energy [24], leading to the improvement of intrinsic electrocatalytic performance and electron transport.…”

“…While significant progress has been made in the study of binary transition metal phosphides as bifunctional catalysts [12,22,23], the application of ternary metal phosphides in hydrogen or oxygen evolution reactions has been scarcely reported, to the best of our knowledge. In addition, previous spectroscopic and theoretical studies demonstrated that the incorporation of additional metal atoms into HER and OER catalysts is crucial for enhancing their electrocatalytic activity by tuning of the electronic structure [24][25][26][27]. Considering the excellent catalytic potential of phosphide-based materials with electronic structure tunable by atom doping, ternary metal phosphides should be superior bifunctional catalysts for overall water splitting, compared with their binary counterparts.…”

One‐Dimensional Earth‐Abundant Nanomaterials for Water‐Splitting Electrocatalysts

“…For instance, CoP nanocrystals decorated on CNTs were synthesized by the low‐temperature phosphidation of a Co 3 O 4 /CNT precursor 61. Co‐doped iron pyrite nanosheets were interfaced with CNTs (Fe 1–x Co x S 2 /CNT hybrid) by solution reaction of Fe salt, Co salt and thioacetamide, followed by thermal treatment 62. A strong dependence of the Co doping ratio on the HER activity of the Fe 1–x Co x S 2 /CNT hybrid catalyst was found.…”

Hierarchical Co–FeS2/CoS2 heterostructures as a superior bifunctional electrocatalyst

“…Among them, the low-cost, earthabundant iron sulde has attracted much attention as an electrocatalytic material due to its excellent catalytic activity. 7,18 However, the catalytic performance of iron sulde is limited by its low surface area and lack of active sites. 19 If the non-noble metals electrocatalysts are grown on carbon material substrates, doping with homologous elements not only reduces the catalytic resistance but also exposes more active sites.…”