New electrocatalyst developed for ORR

July 30, 2018

Recent research published in a paper in NANO by a team of researchers from Beihang University have fabricated a new type of VNQD-NG as nonprecious metal-based electrocatalyst for oxygen reduction reaction (ORR). The unique structural features of plentiful VN quantum dots with the sizes of 3-6 nm, high surface area and multi-level pores afford considerable structural edges and defects as active sites, maximizing the exposed active sites and providing sufficient electron transport pathways for ORR. This has significant practical and commercial applications.

A team of researchers from Beihang University in Beijing, China has demonstrated a new type of low-cost nonprecious metal-based catalysts as an alternative to platinum-based catalysts for oxygen reduction reaction. In their work, a new type of vanadium nitride quantum dots anchored homogeneously onto nitrogen-doped graphene (denoted as VNQD-NG) is fabricated by a simple hydrothermal method and subsequent ammonia annealing process. The VNQD-NG exhibits high electrocatalytic activity, long durability and high selectivity for ORR, superior to commercially available Pt-C. Their report appears in the forthcoming issue of the journal NANO.

Developing suitable electrocatalysts for ORR is significant to the practical applications of fuel cells and metal-air batteries due to the kinetic sluggishness of ORR with a complex four-electron transfer process. Despite the high efficiency of platinum (Pt) and Pt-based alloys for ORR, their high cost along with the rare reserves in nature largely impedes the large-scale practical application. Therefore, developing low-cost nonprecious metal-based catalysts as an alternative to Pt-based catalysts are crucial. Vanadium nitrite (VN) not only has the similar structure and high density of states to those of above transition-metal nitrides, but also shows good corrosion resistance and high electrical conductivity, holding great promise as an active electrocatalyst for ORR.

The as-prepared VNQD-NG possesses numerous zero-dimensional (0D) VN quantum dots (QDs) with the sizes of 3?6 nm anchored homogeneously onto the surface of nitrogen-doped graphene, affording considerable structural edges and defects as active sites for ORR. Moreover, the VNQD-NG nanosheets can simultaneously construct a three-dimensional (3D) porous architecture to maximize the exposed active sites and provide sufficient electron transport pathways during ORR. Researchers executed cyclic voltammogram (CV) measurements in an aqueous 0.1 M KOH solution to investigate the ORR characteristics of VNQD-NG samples, reflecting a prominent electrocatalytic activity of the VNQD-NG for oxygen reduction. Chronoamperometric measurements show that a strong current response occurs at Pt-C catalyst when 3 M methanol was injected in oxygen-saturated solution, whereas the VNQD-NG maintains a stable current without any distinct response. Apparently, the VNQD-NG hybrid exhibits a high selectivity to methanol in the alkaline electrolyte, tolerance to crossover effects caused by fuel molecules permeating through the polymer membrane. Researchers also conducted the rotating ring-disk electrode (RRDE) measurements to verify the ORR electrochemical kinetics of VNQD-NG, displaying a comparable ORR onset potential to that of Pt-C catalyst, and higher electron transfer number (n) and kinetic-limiting current density (Jk) than that of commercial Pt-C and other non-Pt catalysts. The current-time (i?t) choronoamperometric response for VNQD-NG reveals a quite low attenuation of 77 % after 30 000 s, which provides further evidence that the stability of VNQD-NG is superior to that of commercial Pt-C (60 %).

VNQD-NG exhibits high electrocatalytic activity, high selectivity and long durability for ORR, better than commercially available Pt-C. These achievements could provide an extension of developing various other 3D porous metal nitride quantum dots onto graphene for broad applications in sensors, catalysis, and other electronic devices.
This work was financially supported by National Science Foundation of China (No.51572007), the Scientific Research Foundation for the Returned Overseas Chinese Scholars (No.37-7290-01), State Education Ministry, the "Recruitment Program of Global Experts".

Corresponding author for this study is Shubin Yang,

For more insight into the research described, readers are invited to access the paper on NANO.


Caption: Vanadium nitride quantum dots anchored homogeneously onto nitrogen-doped graphene (VNQD-NG) was fabricated. The unique structural features of VNQD-NG including the plentiful VN quantum dots, high surface area and multi-level pores are favorable for the ORR. VNQD-NG exhibits high electrocatalytic activity, long durability and high selectivity for ORR, superior to commercially available Pt-C.

NANO is an international peer-reviewed monthly journal for nanoscience and nanotechnology that presents forefront fundamental research and new emerging topics. It features timely scientific reports of new results and technical breakthroughs and publishes interesting review articles about recent hot issues.

World Scientific

Related Active Sites Articles from Brightsurf:

'Cool' sampling sites more likely to show false trends
Data collected by citizen science initiatives, museums and national parks is an important basis for research on biodiversity change.

Binding sites for protein-making machinery
ETH Zurich researchers can predict how tightly a cell's protein synthesis machinery will bind to RNA sequences - even when dealing with many billions of different RNA sequences.

Differences between discs of active and non-active galaxies detected for the first time
A study led by researchers at the Instituto de Astrofísica de Canarias (IAC), making comparison between the discs of several pairs of spiral galaxies, active and non-active, concludes that in the discs of the former the rotational motion of the stars is of greater importance.

Seroprevalence of antibodies to SARS-CoV-2 in 10 US sites
This study estimates how common SARS-CoV-2 antibodies are in convenience samples from 10 geographic sites in the United States.

'Growing' active sites on quantum dots for robust H2 photogeneration
Chinese researchers had achieved site- and spatial- selective integration of earth-abundant metal ions in semiconductor quantum dots (QDs) for efficient and robust photocatalytic H2 evolution from water.

Solar and wind energy sites mapped globally for the first time
Researchers at the University of Southampton have mapped the global locations of major renewable energy sites, providing a valuable resource to help assess their potential environmental impact.

Big variability in blood pressure readings between anatomical sites
Blood pressure readings taken from neuroscience intensive care unit (NSICU) patients had marked differences between opposite sides of the body and different anatomical sites in each individual.

Social networking sites affect nurses' performance
Addiction to social networking sites reduces nurses' performance and affects their ability to concentrate on assigned tasks, according to a study published in the Journal of Advanced Nursing.

Monitoring CO2 leakage sites on the ocean floor
Injecting carbon dioxide (CO2) deep below the seabed could be an important strategy for mitigating climate change, according to some experts.

Keeping active or becoming more active in middle and older age linked to longer life
Keeping physically active or becoming more active during middle and older age is associated with a lower risk of death, regardless of past activity levels or existing health conditions, suggests a large UK study published by The BMJ today.

Read More: Active Sites News and Active Sites Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to