Polypyrrole Hollow Microspheres with Boosted Hydrophilic Properties for Enhanced Hydrogen Evolution Water Dissociation Kinetics

Abstract

The water dissociation step (H 2 O + M + e − → M − H ads + OH − ) is a crucial one toward achieving high-performance hydrogen evolution reaction (HER). The application of electronic conducting polymers (ECPs), such as polypyrrole (PPy), as the electrocatalyst for HER is rarely reported because of their poor adsorption energy per water molecule, which hinders the Volmer step. Herein, we strongly enrich PPy hollow microspheres (PPy-HMS) with attractive HER activity by enhancing their hydrophilic properties through hybridization with good water affinity SiO 2 . The as-prepared PPy-coated SiO 2 (PPy@SiO 2 -HMS) achieves a current density of 10 mA cm −2 at −123 mV, which is lower than that of pristine PPy-HMS (−192 mV). Raman and X-ray photospectroscopy analyses reveal that the enhanced HER catalytic capability can be attributed to the strong electronic couplings between PPy and SiO 2 , and this improves the adsorption energy per water molecule and in turn accelerates the water dissociation kinetics on PPy. This work highlights the potential application of lowcost ECPs as promising electrocatalysts for water electrolysis.

Electrocatalyst design for the conversion of energy molecules: electronic state modulation and mass transport regulation

“…Modifying the catalyst with a high surface energy substance is another route to superhydrophobicity. [187][188][189][190] The electronic conducting polymers (ECPs) have excellent charge transfer properties, but as the catalyst for HER is rarely reported because of their poor adsorption energy per water molecule, which hinders the Volmer step. To enhance the hydrophilic properties of PPy (one ECPs), Zheng et al designed a hybridization strategy by adopting a good water affinity SiO 2 .…”

“…11e), convincingly confirming that the Ppy-SiO 2 -HMS exhibits excellent water affinity than Ppy-HMS. 187 Thus, the hydrophilic surface of Ppy-SiO 2 -HMS will display improved water dissociation kinetics. With the excellent surface character, the Ppy-SiO 2 -HMS exhibits a lower overpotential of À123 mV at 10 mA cm À2 than À192 mV at 10 mA cm À2 of Ppy-HMS (Fig.…”

Facile Polypyrrole/NASICON (PPy/Na3Fe2(SO4)2(PO4)) Electrode Materials for the Hydrogen Evolution Reaction

“…To get around these restrictions, different composites of these materials were synthesized for electrocatalytic hydrogen evolution reactions, which have the advantages of being economical, noble, and toxic metal-free, environmentally friendly, and having extremely high stability. Conducting polymer-based nanocomposites with metals, bimetals, and their compounds emerged as one of the promising candidates for the HER in recent years due to the vibrant superiority of compositional and morphological flexibilities, easy synthesis, and tunable diversity. − Conducting polymer-based composite materials also has advantages concerning their cost-effectiveness, processability, and environmentally friendly and nontoxic nature. − Due to the synergistic effects of the polymer matrix and the nanofiller, conductive polymer nanocomposites are made conductive by combining a polymer matrix with nanofillers which exhibit excellent catalytic activity toward the HER. Conducting polymers that have been explored for the HER are polyaniline, polythiophene, polyindole, poly o -aminophenol, polypyrrole, , poly­(3,4-ethylenedioxythiophene) (PEDOT) including their composites. ,, Polypyrrole (PPy) is a high potential material for energy conversion and storage .…”

“…NASICON-structured Na 3 Fe 2 (SO 4 ) 2 (PO 4 ) (hereafter termed as NFS), on the other side, has a much high affinity toward water and can easily incorporate with the PPy matrix. The nitrogen in the PPy ring can easily interact with the metal center. ,, Due to the conjugation in PPy moieties, the electron sharing capability is enhanced from electron-rich nitrogen for PPy to NFS which facilitates better charge transfer. Also, the PPy backbone contains the positive charge centers, which also enhances the charge transfer by interacting with the electron-rich centers.…”

Electrophoretic Deposition of MoSe2–MoOx Nanosheets for Enhanced Electrocatalytic Hydrogen Evolution Reaction

“…Of many non-noble-metal HER electrocatalysts, transition-metal dichalcogenides, − transition-metal oxides/hydroxides, − black phosphorous, carbon-based materials (i.e., carbon nanotubes, graphene, graphene oxide, and carbon nanostructures), conducting polymers such as polypyrrole and polyaniline, − and so forth stand out as the traditionally striking HER electrochemical catalysts. Two-dimensional transition-metal dichalcogenides (2D-TMDCs) including MoS 2 , − WS 2 , MoSe 2 , and WSe 2 have gained huge attention owing to their tunable catalytic activities.…”