Water-Phase Lateral Interconnecting Quantum Dots as Free-Floating 2D Film Assembled by Hydrogen-Bonding Interactions to Acquire Excellent Electrocatalytic Activity

Feifei Wang; Qiguan Wang; Sumin Wang; Kai Zhang; Siqin Jia; Jian Chen; Xinhai Wang

doi:10.1021/acsnano.2c00507

Water-Phase Lateral Interconnecting Quantum Dots as Free-Floating 2D Film Assembled by Hydrogen-Bonding Interactions to Acquire Excellent Electrocatalytic Activity

ACS Nano. 2022 Jun 28;16(6):9049-9061. doi: 10.1021/acsnano.2c00507. Epub 2022 Jun 13.

Authors

Feifei Wang¹, Qiguan Wang¹, Sumin Wang¹, Kai Zhang¹, Siqin Jia, Jian Chen¹, Xinhai Wang²

Affiliations

¹ The Youth Innovation Team of Shaanxi Universities, Shaanxi Key Laboratory of Photoelectric Functional Materials and Devices, School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an 710021, China.
² School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China.

PMID: 35695291
DOI: 10.1021/acsnano.2c00507

Abstract

Supramolecular self-assembly of nanoparticles in two orthogonal directions would potentially allow one to fabricate nanomaterials with fascinating properties. In this study of a hydrothermal polycondensation of melamine/cyanuric acid, graphitic carbon nitride-based quantum dots (CNQD, ∼2 nm) are in situ arranged along two orthogonal directions through lateral hydrogen bonding, and free-floating two-dimensional hydrogen-bonded films of CNQD (2D CNQD) are built. On the basis of the universality of this hydrothermal in situ supramolecular self-assembly technique, 2D films linked by other quantum dots such as sulfur-doped graphitic carbon nitride and CdTe are also constructed. With the benefits of stimuli responsiveness and the reversibility of hydrogen bonds, controllable assembly/disassembly of the 2D CNQD film is feasibly achieved by external stimuli such as inletting CO₂/N₂, which endows the assembled 2D CNQD films optimal electrochemical superiorities of both 2D film and zero-dimensional (0D) quantum dots. Accordingly, the 2D CNQD film delivers a high bifunctional activity in both a nitrogen reduction reaction (NRR) and an oxygen evolution reaction (OER). Especially in NRR, it exhibits the high yield rate of NH₃ reaching 75.07 μg h^-1 mg^-1 at -0.85 V versus reversible hydrogen electrode at ambient condition. Strikingly, the power density of the rechargeable Zn-N₂ battery using 2D CNQD film as cathode reaches 31.94 mW cm^-2, outperforming the majority of Zn-N₂ batteries. Density functional theory calculations proved the promoted adsorption of N₂ and stabilized NRR intermediates on 2D CNQD cooperated by multiply hydrogen-bonding interactions are the main reasons for the excellent NRR electrocatalytic performances. This work hints that hydrothermal in situ supramolecular self-assembly is a feasible and direct way to integrate 0D quantum dots into 2D directional arrays, and the hydrogen bond that interlinks enables this free-floating 2D structure to maintain the electrochemical superiority of both 0D and 2D structures.

Keywords: Free-floating 2D film; Hydrogen bond; Nitrogen reduction reaction; Oxygen evolution reaction; Quantum dot.