Unraveling the Electrocatalytic Activity in HMF Oxidation to FDCA by Fine‐Tuning the Degree of NiOOH Phase Over Ni Nanoparticles Supported on Graphene Oxide

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 27; pp. e2400779 - n/a
• Main Authors: Klinyod, Sorasak, Yodsin, Nuttapon, Nguyen, Mai Thanh, Pasom, Zikkawas, Assavapanumat, Sunpet, Ketkaew, Marisa, Kidkhunthod, Pinit, Yonezawa, Tetsu, Namuangruk, Supawadee, Wattanakit, Chularat
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.07.2024
• Subjects: Density functional theory; Electrocatalysts; electrochemical pathways; Graphene; HMF electrooxidation; Metal surfaces; NiNPs/GO material; Oxidation; periodic DFT calculations; valence state of Ni; HMF electrooxidation; electrochemical pathways; periodic DFT calculations; NiNPs/GO material; valence state of Ni
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202400779

The development of an efficient electrocatalyst for HMF oxidation to FDCA has been in the early stages. Herein, the NiNPs/GO‐Ni‐foam is fabricated as an electrocatalyst for FDCA production. However, the electrocatalytic performance of the untreated NiNPs/GO‐Ni‐foam is observed with moderate Faradaic efficiency (FE) (73.0%) and FDCA yield (80.2%). By electrochemically treating the NiNPs/GO‐Ni‐foam in an alkaline solution with positive potential at different treatment durations, the degree of NiOOH on metal surfaces is changed. The distinctive electrocatalytic activity obtained when using the different NiOOH degrees allows to understand the crucial impact of NiOOH species in HMF electrooxidation. Enhancing the portion of the NiOOH phase on the electrocatalyst surface improves electrocatalytic activity in terms of FE and FDCA yield up to 94.8±4.8% and 86.9±4.1%, respectively. Interestingly, as long as the NiOOH portion on the electrocatalyst surface is preserved or regenerated, the electrocatalyst performance can be intact even after several catalytic cycles. The theoretical study via density functional theory (DFT) also agrees with the experimental observations and confirms that the NiOOH phase facilitates the electrochemical transformation of HMF to FDCA through the HMFCA pathway, and the potential limiting step of the overall reaction is the oxidation of FFCA to FDCA. Systematic creation of the high valence state of the NiOOH (Ni3+) phase derived from the surface reconstruction of Ni (Ni0) metal allows to understand the crucial impact of NiOOH species on the electrocatalytic pathway of HMF electrooxidation, leading to the new concept for rationally designing the electrocatalyst for electrooxidation.