Insights into Water Interaction at the Interface of Nitrogen-Functionalized Hydrothermal Carbons

Abstract

Hydrothermal carbon (HTC) derived from biomass is a class of cost-efficient, eco-friendly functional carbon materials with various potential applications. In this work, solidstate nuclear magnetic resonance (NMR), longitudinal (T 1 ) relaxation time, and diffusion NMR were employed to investigate the structure and water dynamics for HTC and nitrogenfunctionalized hydrothermal carbon (N-HTC) samples ((N)-HTC). Results showed that the presence of N-functional groups influences the water interaction with (N)-HTC more strongly than surface area, pore size distribution, or oxygenated functional groups. Furthermore, the degree of water interaction can be tuned by adjusting the synthesis temperature and the precursor ratio. Water motion was more strongly inhibited in N-HTC than in N-free HTC, thereby suggesting the existence of a differently structured hydration shell around N-HTC particles. In addition, the diffusion data of water in the N-HTC material show two components that do not exchange on the time scale of the experiment (tens of milliseconds), indicating a significant fraction of slow mobile water that exists inside the structure of N-HTC. 1 H− 2 H isotope exchange and cross-polarization NMR results show this internal water only in a near-surface layer of the N-HTC particles. Based on these findings, a model for water interaction with (N)-HTC particles is proposed.

Tuning of Reciprocal Carbon‐Electrode Properties for an Optimized Hydrogen Evolution.

“…This demonstrates the important effect of heteroatoms for improving the aqueous affinity of the carbon surface. This observation is supported by the previous work, which demonstrated stronger interactions with water and hydrothermal carbon surfaces when they contain nitrogen [17] . Furthermore, the heteroatoms lead to a higher capacity of the sample (Figure S4).…”

Laser-generated high entropy metallic glass nanoparticles as bifunctional electrocatalysts

“…Although the graphitic shells may limit access to the metal atoms during the catalytic reactions, the highly oxidizing conditions in OER are likely to oxidize the carbon next to the metallic components leading to corrosion of the carbon [103,104]. The detected redox peaks in the cyclic voltammograms are a very good indication that the metal atoms take part in the catalytic reactions during the potential scans also under ORR conditions (Figs.…”

Conductivity Mechanism in Ionic 2D Carbon Nitrides: From Hydrated Ion Motion to Enhanced Photocatalysis

“…The mechanism behind a faster ion motion at higher temperatures requires further studies. A reason might be an additional lithium motion scheme in confined spaces, textural voids, grain boundaries, or at the particle surface due to multilayer water adsorption [ 56 ] in contrast to the ion motion inside the pores, which are more hindered due to interaction of the ion (or its hydration shell) with the backbone, resulting in a small change of the diffusion coefficient with temperature.…”