Carbide-directed enhancement of electrochemical hydrogen evolution reaction on tungsten carbide–oxide heterostructure

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2022-12, Vol.450, p.137915, Article 137915
• Main Authors: Ngo, Yen-Linh Thi, Bhamu, K.C., Voronova, Anastasiia, Jana, Jayasmita, Kang, Sung Gu, Chung, Jin Suk, Choi, Won Mook, Jang, Jong Hyun, Hur, Seung Hyun, Seo, Bora
• Format: Article
• Language: English
• Subjects: Carbon dots; Electrocatalyst; Hydrogen evolution reaction; Tungsten carbide; Tungsten oxide
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.137915

A new preparation approach for high density of carbide-oxide heterointerfaces was demonstrated. The resulting carbide-oxide heterostructured catalyst showed very high hydrogen evolution reaction (HER) activity compared to the state-of-the-art carbide-based HER catalysts. More importantly, the single-cell test using WO(3−x)−WCy/CDs as the cathode in polymer electrolyte membrane water electrolysis cell showed a current density of 10 mA cm−2 with a cell voltage of only 1.47 V, which is very close to that for Pt/C (1.41 V). [Display omitted] •Catalyst with a high density of carbide-oxide heterointerfaces was prepared.•The catalyst showed superior electrocatalytic hydrogen evolution reaction activity.•Its single-cell performance is close to that for the benchmark Pt/C catalyst.•Theoretical calculations provided insight into the carbide-directed enhancement.•Correlation between composition and HER activity suggested the optimum W–C ratio. Carbide–oxide heterointerfaces have been known to be responsible for electrochemical activity, however, it is rarely investigated in tungsten carbide-oxide heterostructure for the hydrogen evolution reaction (HER). Furthermore, typical carbide preparation includes carbonization of oxide under gaseous carbon sources at a high temperature, resulting in sintering and collapse of the heterostructures. In this work, nano-sized carbon dots (CDs, ∼2 nm in diameter) were adopted as carbon sources and dispersed on tungsten oxide nanorods allowing abundant nucleation sites for oxide-to-carbide conversion, resulting in high density of carbide-oxide heterointerfaces. The resulting tungsten carbide-oxide heterostructure decorated with carbon dots (WO(3−x) − WCy/CDs) exhibited superior electrocatalytic activity toward the HER with a low overpotential of 65 mV at a current density of − 10 mA cm−2 in acidic media. This performance is among the best electrocatalytic activities compared to the state-of-the-art tungsten carbide-based electrocatalysts. Importantly, the single-cell test using WO(3−x) − WCy/CDs as the cathode showed a current density of 10 mA cm−2 with a cell voltage of only 1.47 V, which is very close to that for Pt/C (1.41 V). In addition, a combined analysis of the X-ray spectroscopic and electrochemical results suggested an optimal W–C ratio in the tungsten carbide-oxide composite to guarantee the high HER activity. Theoretical calculations provided more insight into the carbide-directed enhancement of the electrocatalytic activ