Research Article Issue
Multiple structural defects in ultrathin NiFe-LDH nanosheets synergistically and remarkably boost water oxidation reaction
Nano Research 2022, 15 (1): 310-316
Published: 03 June 2021

Modifying electrocatalysts nanostructures and tuning their electronic properties through defects-oriented synthetic strategies are essential to improve the oxygen evolution reaction (OER) performance of electrocatalysts. Current synthetic strategies about electrocatalysts mainly target the single or double structural defects, while the researches about the synergistic effect of multiple structural defects are rare. In this work, the ultrathin NiFe layered double hydroxide nanosheets with a holey structure, oxygen vacancies and Ni3+ defects on nickel foam (NiFe-LDH-NSs/NF) are prepared by employing a simple and green H2O2-assisted etching method. The synergistic effect of the above three defects leads to the exposure of more active sites and significant improvement of the intrinsic activity. The optimized catalyst exhibits an excellent OER performance with an extraordinarily low overpotential of 170 mV at 10 mA·cm−2 and a small Tafel slope of 39.3 mV·dec−1 in 1 M KOH solution. Density functional theory calculations reveal this OER performance arises from pseudo re-oxidized metal-stable Ni3+ near oxygen vacancies (Ovac), which suppresses 3d-eg of Ni-site and elevates d-band center towards the competitively low electron-transfer barrier. This work provides a new insight to fabricate advanced electrocatalysts for renewable energy conversion technologies.

Research Article Issue
Enhancing catalytic H2 generation by surface electronic tuning of systematically controlled Pt-Pb nanocrystals
Nano Research 2019, 12 (9): 2335-2340
Published: 01 February 2019

Although many previous studies have shown that the shape-control of nanocrystal (NCs) is an efficient strategy to improve the catalytic performance, these syntheses were conducted under very different conditions, which are not suitable for the shape-dependent properties studies as well as catalysis optimization. Herein, we demonstrate an effective method for the selective synthesis of well-defined PtPb NCs in a highly controllable manner. Four distinct PtPb NCs, namely PtPb peanut nanocrystals, PtPb hexagonal nanoplates, PtPb octahedra nanocrystals (ONCs) and PtPb nanoparticles have been selectively prepared in the presence of different phenols. Significantly, we found that the created PtPb NCs/C shows the shape-dependent activity with the optimized PtPb ONCs/C being the most active for the ethanol reforming to H2, 22.4 times higher than the commercial Pt/C. The high performance of PtPb ONCs/C has been also successfully expanded into other polyhydric alcohols reformings. X-ray photoelectron spectroscopy (XPS) reveals that the high Pt(0)/Pt(Ⅱ) ratio in PtPb NCs/C enhances the alcohols reforming. The density functional theory (DFT) studies show the PtPb ONCs possess the highest surface averaged electronic occupation for unit Pt-atom, matching well with XPS results. The PtPb ONCs/C also displays excellent durability with limited activity decay and negligible structure/composition changes after ten cycles. This work demonstrates an important advance in the high-level control of metallic nanostructures to tune the catalytic activities.

Research Article Issue
Facet and dimensionality control of Pt nanostructures for efficient oxygen reduction and methanol oxidation electrocatalysts
Nano Research 2016, 9 (9): 2811-2821
Published: 29 July 2016

The control of the size, composition, and shape of platinum nanocrystals has attracted much attention recently, mostly due to their unique properties and related catalytic functionalities. However, the realization of platinum nanocrystals with controlled exposed facets and dimensionality remains a significant challenge. Herein, we show an efficient synthetic strategy to selectively prepare highly controllable platinum nanocrystals with distinct dimensionalities from onedimensional nanowires to zero-dimensional octahedra. Although the synthesis of platinum nanowires has been reported multiple times, the synthetic approach reported herein is much more novel and robust and ultimately results in high yields of high-quality platinum nanowires. Such dimensionality tuning on {111} facet dominated platinum nanocrystals allows us to firstly investigate the effect of the number of edges/corners on the electrocatalytic properties. Our results show that the synthesized platinum nanocrystals exhibit very interesting dimensionality-dependent electrocatalytic activity towards both the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR), in which one-dimensional platinum nanowires with minimized edges/corners show enhanced electrocatalytic activities with respect to zero-dimensional platinum octahedra. Our dimensionality tuning also provides Pt nanowires with superior durability for the oxygen reduction reaction with negligible activity decay over the course of 30, 000 potential sweeps. The present work highlights that the {111} facet bound platinum nanowires with minimized edges/corners are indeed promising candidates as electrocatalysts with excellent activity and superior durability.

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