Electrocatalytic Hydrogen Evolution from Molybdenum Sulfide–Polymer Composite Films on Carbon Electrodes

Abstract

The design of more efficient catalytic electrodes remains an important objective for the development of water splitting electrolyzers. In this context a structured composite cathode material has been synthesized by electrodeposition of molybdenum sulfide (MoSx) into a poly(pyrrole-alkylammonium) matrix, previously coated onto carbon electrodes by oxidative electropolymerization of a pyrrole-alkylammonium monomer. The composite material showed an efficient electrocatalytic activity toward proton reduction and the hydrogen evolution reaction (HER). Data from Tafel plots have demonstrated that the electron transfer rate in the composite films is fast, in agreement with the high catalytic activity of this cathode material. Bulk electrolysis of acidic water at carbon foam electrodes modified with the composite have shown that the cathodes display a high catalytic activity and a reasonable operational stability, largely exceeding that of regular amorphous MoSx electrodeposited on naked carbon foam. The enhanced catalytic performances of the composite electrode material were attributed to the structuration of the composite, which led to a homogeneous distribution of the catalyst on the carbon foam network, as shown by SEM characterizations.

Polymer-Brush-Templated Three-Dimensional Molybdenum Sulfide Catalyst for Hydrogen Evolution

“…On the basis of these data, the TOF at η = 250 mV was calculated (Figure , inset). It is noted that the TOFs of these composites are quite high and are 1 order of magnitude higher than that of a previously reported MoS x –polymer composite system …”

“…MoS x –polymer composites have previously been utilized for a number of applications. − The incorporation of MoS 2 within a polymer matrix has resulted in improved thermal, mechanical, and tribological properties of the materials. , Addition of MoS 2 to conductive polymers such as polypyrrole, polyaniline, and poly­(3,4-ethylenedioxythiophene) leads to better supercapacitors . Because MoS x has been reported as an archetypical nonprecious HER catalyst, − MoS x –polymer hybrids have also been evaluated for HER. − However, the performance of these composites is still modest.…”

New Methods for the Functionalization of Polymer Matrices with Thiomolybdate Clusters Applied for Hydrogen Evolution Reaction Catalysis

“…[8,9] In particular, molybdenum sulfides and their molecular analogues, thiomolybdate clusters, [10] have been used as high-performance HER catalysts under electrochemical and photochemical conditions. [11][12][13][14][15][16][17][18][19][20][21] These clusters are also known for their sulfur resistance (e.g., against sulfur poisoning with sulfide). [22] However, thiomolybdate clusters are not long-term stable under typical HER conditions, as ligand exchange reactions lead to the deactivation of the catalyst.…”

Synergistic CoN-Decorated Pt Catalyst on Two-Dimensional Porous Co–N-Doped Carbon Nanosheet for Enhanced Oxygen Reduction Activity and Durability

“…Conventionally, carbon blacks such as Vulcan XC72R and acetylene black are common support materials for commercial ORR electrocatalysts due to their high graphitization, which is beneficial for carbon corrosion tolerance. However, they possess low surface area, a less porous structure, and surface functional groups and thus sometimes need to be pretreated by physical or chemical treatments. − Other porous carbons including Ketjen black and oxidized acetylene black have very high surface areas and internal pores (e.g., micropores), which are favorable for Pt deposition. However, a number of Pt nanoparticles (NPs) can be deposited into micropores with very small openings, inhibiting particle contact with ionomers as well as both protons and reactant gases, thus leading to low performance. − Recently, functionalized hierarchical or mesoporous carbon materials with nitrogen-containing groups have been reported to result in favorable metal–support interactions, which could highly promote the activity and durability of the electrocatalysts. − …”