Revealing the effect of electrocatalytic performance boost during hydrogen evolution reaction on free-standing SWCNT film electrode

Abstract

Large-scale sustainable hydrogen production by water electrolysis requires a highly active yet low-cost hydrogen evolution reaction (HER) electrocatalyst. Conductive carbon nanomaterials with high surface areas are promising candidates for this purpose. In this contribution, single-walled carbon nanotubes (SWCNTs) are assembled into free-standing films and directly used as HER electrodes. During the initial 20 h of electrocatalytic performance in galvanostatic conditions, the films undergo activation, which results in a gradual overpotential decrease to the value of 225 mV. Transient physicochemical properties of the films at various activation stages are characterized to reveal the material features responsible for the activity boost. Results indicate that partial oxidation of iron nanoparticles encapsulated in SWCNTs is the major contributor to the activity enhancement. Furthermore, besides high activity, the material, composed of only earth-abundant elements, possesses exceptional performance stability, with no activity loss for 200 h of galvanostatic performance at − 10 mA cm−2. In conclusion, the work presents the strategy of engineering a highly active HER electrode composed of widely available elements and provides new insights into the origins of electrocatalytic performance of SWCNT-based materials in alkaline HER.

Intermetallic FeSb2 in a Multifunctional Role of Highly Selective and Efficient Adsorbent, Catalyst, and HER Electrocatalyst

“…Both spectra display similar features having signals at 706.6 and 719.7 eV, which could be assigned to metallic Fe 2p 3/2 and Fe 2p 1/2 , respectively . The peaks at 711.5 and 724.6 eV are attributed to Fe 2p 3/2 and Fe 2p 1/2 in Fe 2 O 3 and other Fe­(III) compounds, respectively . The spectra clearly indicate the change in the relative intensity of the signals after electrochemical measurements.…”

“…The X-ray Photoelectron Spectroscopy (XPS) spectra (Figure f) of Fe 2p were collected before and after electrolysis to study the effect of HER on the chemical states of iron present in the electrode. Both spectra display similar features having signals at 706.6 and 719.7 eV, which could be assigned to metallic Fe 2p 3/2 and Fe 2p 1/2 , respectively . The peaks at 711.5 and 724.6 eV are attributed to Fe 2p 3/2 and Fe 2p 1/2 in Fe 2 O 3 and other Fe­(III) compounds, respectively .…”

“…Both spectra display similar features having signals at 706.6 and 719.7 eV, which could be assigned to metallic Fe 2p 3/2 and Fe 2p 1/2 , respectively. 34 The peaks at 711. after electrocatalytic study, Figure S2 and Table S2). Tafel plots presented in Figure 3b, were obtained from the corresponding Linear sweep voltammetry (LSV) curves.…”

Unveiling the Transformative Potential of SWCNT/In2O3 Heterostructures as High-Performance Catalysts for Overall Water Splitting

“…Kordek-Khalil et al discussed the HER behavior of a freestanding SWCNT film catalyst in an alkaline medium, which shows a 225 mV overpotential and 135 mV dec −1 Tafel slope. 61 Pal et al examined the HER behavior via band modulation of covalently connected CNTs in an acidic medium, 62 showing the overpotentials of 480 and 300 mV for SWCNT-OH and 3D MWCNTs, respectively. In the present work, the In 2 O 3 /SWCNT-4 heterostructure catalyst shows the lowest overpotential of 141 mV, a low Tafel slope of 107.7 mV dec −1 , and outstanding stability for 24 h. It is also concluded that the In 2 O 3 /SWCNT-4 heterostructure catalyst shows excellent bifunctional electrocatalytic activities.…”

“…Kordek-Khalil et al. discussed the HER behavior of a free-standing SWCNT film catalyst in an alkaline medium, which shows a 225 mV overpotential and 135 mV dec –1 Tafel slope . Pal et al examined the HER behavior via band modulation of covalently connected CNTs in an acidic medium, showing the overpotentials of 480 and 300 mV for SWCNT-OH and 3D MWCNTs, respectively.…”