Tailoring the d-band center of N-doped carbon nanotube arrays with Co4N nanoparticles and single-atom Co for a superior hydrogen evolution reaction

Abstract

A 3D self-supported integrated electrode, consisting of heteroatomic nitrogen-doped carbon nanotube arrays on carbon cloth with confined ultrafine Co4N nanoparticles and a distribution of anchored single-atom Co, is fabricated via a cobalt-catalyzed growth strategy using dicyandiamide as the nitrogen and carbon source and a layered cobalt hydroxide-nitrate salt as the precursor. The abundance of exposed active sites, namely, the Co4N nanoparticles, single-atom Co, and heteroatomic N-doped carbon nanotubes, and multiple synergistic effects among these components provide suitable tailoring of the d-band center for facilitating vectorial electron transfer and efficient electrocatalysis. Benefiting from the merits of its structural features and electronic configuration, the prepared electrode exhibits robust performance toward the hydrogen evolution reaction with overpotentials of only 78 and 86 mV at 10 mA cm−2 in acidic and basic electrolytes, respectively. Density functional theory calculations and X-ray photoelectron spectroscopy valence band measurements reveal that the effective tailoring of the d-band center by Co4N nanoparticles plays a crucial role in optimizing the hydrogen adsorption free energy to a more thermoneutral value for efficient electrocatalysis.

Synergistic effect of Co catalysts with atomically dispersed CoNx active sites on ammonia borane hydrolysis for hydrogen generation

“…The ratio of I D /I G was determined to be 0.6, indicative of a high degree of graphitization of the prepared catalyst 31 and signicant structural defects or microstructural rearrangement of the atoms in Co/Co-N-CNT-33-800T, due to the presence of N dopants 32 and Co dopants. 33 The surface area and porosity of the Co-N-CNT-33-800T support were measured from a nitrogen adsorptiondesorption isotherm at liquid nitrogen temperature. As shown in Fig.…”

“…Co(acac) 2 can be atomically dispersed in DCD-350, due to weak van der Waals forces. Various nominal weight ratios of Co metals to DCD-350 (1 : 33.3, 1 : 40, 1 : 50, 1 : 66.6, 1 : 100, 1 : 125, 1 : 166.6, and 1 : 250) at 800 C were denoted as Co/CoN x -CNT-m (m ¼ 33,40,50,66,100,125,166,250) respectively. DCD-350 (10 g) and Co(acac) 2 (1.3 g, 5.05 mmol) were weighed and manually ground into ne particles.…”

“…This resulted in a mixture of both Co nanoparticles and atomically dispersed Co atoms, a phenomenon also observed in the CNT formation with Fe-N x active sites without SiO 2 coating 44 and in the formation of Co@CoSAs/N-CNTs. 33 Catalytic activity performance Effects of carbonization temperatures on hydrogen production. For catalytic testing, the as-synthesized Co/CoN x -CNT-33-800T sample (40 mg) was rst dispersed in an aqueous ammonia borane solution (40 mg in 1 mL) at 40 C. Fig.…”

Strategies for Electrochemically Sustainable H2 Production in Acid

“…[ 72 ] During the pyrolysis preparation of Co‐based materials, multiple components involving single atom Co species were formed on carbons, and all components have beneficial effects for acidic HER. [ 73 , 74 , 75 ] However, the complex active components make it difficult to explore the intrinsic properties of single atom Co species. Recently, there were two methods reported to obtain the pure single atom Co catalysts: one is the pyrolysis of Zn/Co‐containing metal‐organic framework compound; [ 76 ] the other is laser irradiation to extract Co species and convert them to single atom Co. [ 77 ] In both approaches, the single atom Co was firmly anchored by N coordination on the C lattice, forming the stable and active Co species.…”

Evaluation and of University Building Design Effect Based on Multisensor Perception and Data Security

“…To meet these ever-changing and increasing requirements, all participants are researching and improving the design. From ancient craftsmen at home and abroad to today's engineers and scholars in many fields such as architecture, engineering, environment, and materials, a lot of research on architectural design has been carried out [17,18]. However, the construction industry is also an industry with high energy consumption and high pollution.…”