Cobalt Nanocrystals Encapsulated in Heteroatom‐Rich Porous Carbons Derived from Conjugated Microporous Polymers for Efficient Electrocatalytic Hydrogen Evolution

Abstract

Cobalt nanocrystals encapsulated in N,O-dual-doped porous carbons as efficient and stable electrocatalysts for hydrogen evolution reaction (HER) are reported. A heteroatom-rich-conjugated microporous polymer is first chemically deposited on a carbon fiber cloth, and after addition of a cobalt salt, pyrolyzed to produce a heteroatom-doped C/Co nanocrystal composite. With this process, the use of additional binders for preparation of electrodes can be avoided. With a trace cobalt loading (0.46 wt%), the electrodes achieve a low Tafel slope of 46 mV dec and overpotential of only 69 mV at a current density of 10 mA cm in 0.5 m H SO . Experimental and computational studies reveal that the superior HER behavior is due to a decreased free energy of hydrogen adsorption, induced by i) electrons transferred from the cobalt nanocrystals to graphite layers and ii) N,O-dual doping reduced the Fermi level of neighboring C atoms.

Improved CO2 Uptake and Supercapacitive Energy Storage Using Heteroatom‐Rich Porous Carbons Derived from Conjugated Microporous Polyaminoanthraquinone Networks

“…The N1s spectra of PAQCB‐900 and PAQTB‐900 can be deconvoluted into three peaks at ∼398.3, ∼400.5, and ∼402.1 eV, which in N‐doped carbon materials are attributed to pyridine‐like, pyrrole‐like and graphitic nitrogen, respectively. XPS reveals that two peaks at ∼531.1 and ∼533.5 eV oxygen owing to C−O and C=O bonds are also present, confirming the presence of N‐ and O‐doping in the microporous carbons.…”

“…Also, conjugated microporous polymers (CMPs) consisting of an extended π‐conjugation and inherent nanopores are a new class of porous materials with three‐dimensional networks, showing promise in applications such as gas capture and separation, chemosensors, heterocatalysis, and energy storage . Beyond that, the rigid π‐conjugated skeletons, carbon‐rich structures, and molecular designable properties of CMPs enable them as suitable precursors for the generation of high surface area and heteroatom‐doped porous carbon materials . Firstly, the robust conjugated structure ensures sufficient framework carbonizability and nanopore stability during carbonization process.…”

Ultra‐High Surface Area Nitrogen‐Doped Carbon Aerogels Derived From a Schiff‐Base Porous Organic Polymer Aerogel for CO2 Storage and Supercapacitors

“…With increasing temperature from 700 to 1000 °C, the intensity ratio of the two bands ( I D / I G ) increased from 0.88 to 1.03. The I D / I G ratio maintained at high values, implying the presence of abundant structural defects, most likely due to the attachment of N and O dopants on the carbon basal plane. The increased I D / I G ratio with increasing temperature is quite similar to the case found on graphene oxide …”

Pore Surface Engineering of Covalent Triazine Frameworks@MoS2 Electrocatalyst for the Hydrogen Evolution Reaction

“…0.1, 0.2, 0.5, 1, 2, and 10) shown as maller Ta fel slope (101, 92, 87, 79, 74, and7 7mVdec À1 )t han as-synthesized CTFs (124 mV dec À1 )a nd free MoS 2 bulk material (107 mV dec À1 ); the lower Tafel slope suggestsf aster catalytic kinetics. [39] MoS 2 nanosheets grown in the confined nanopores of MOFs-derived 3D carbons as electrocatalysts achieved aT afel slope of 51 mV dec À1 . For example, heteroatom-doped CMPs was pyrolyzed and doped with cobalt salt, this electrode material achieved aT afel slope of 46 mV dec À1 at ac urrent density of 10 mA cm À2 in 0.5 mH 2 SO 4 .…”

“…For example, heteroatom-doped CMPs was pyrolyzed and doped with cobalt salt, this electrode material achieved aT afel slope of 46 mV dec À1 at ac urrent density of 10 mA cm À2 in 0.5 mH 2 SO 4 . [39] MoS 2 nanosheets grown in the confined nanopores of MOFs-derived 3D carbons as electrocatalysts achieved aT afel slope of 51 mV dec À1 . [40] Bifunctional hollow rGO spher-es@MoS 2 catalyste xhibited aT afel slope of 105 mV dec À1 .…”