N-Doped Carbon as a Promoted Substrate for Ir Nanoclusters toward Hydrogen Oxidation in Alkaline Electrolytes

Abstract

Development of effective electrocatalysts toward hydrogen oxidation with a low content of noble metals has attracted the attention of the catalytic community. In this work, a novel catalyst composed of nitrogen-doped carbon acting as the substrate and Ir nanoclusters as active species was prepared, which was then employed as an effective catalyst for the hydrogen oxidation reaction (HOR) in an alkaline electrolyte. In 0.1 M KOH, the optimized catalyst provides an exchange current density of 0.144 mA cm Ir −2 for HOR that outperforms the catalytic activity of the commercial Pt/C catalyst with a Pt content of 20 wt %. The substrate induces highly active Ir sites that markedly boosted the electrocatalytic activity for HOR. The nitrogen-doped carbon substrate increases the stability of Ir nanoclusters and decreases the absorption energy of hydrogen on Ir sites; at the same time, the higher electrostatic potential around the adsorbed hydrogen on Ir/N-doped carbon also enables them to be easily attracted by OH − species, both of which enhanced the catalytic activity. The excellent catalytic activity and the understanding shown here will give some hints for the development of HOR catalysts used in alkaline electrolytes.

Tailoring Interfacial Charge Transfer of Epitaxially Grown Ir Clusters for Boosting Hydrogen Oxidation Reaction

“…[31][32][33][34][35][36] The Ir metal shows inferior HOR catalytic ability in alkaline solution compared to Pt, [1] despite its more active interaction with hydroxyl species (OH ad ) than Pt. [1,6] In order to improve the HOR kinetics of Ir catalysts, Ir was alloyed with transitional metals such as Ni [37,38] and Mo, 30 was loaded on nitrogen-doped carbon, [39] and was hybridized with Pd nanosheets, 29 which can achieve an optimal balance between HBE and hydroxide binding energy. The interfacial charge transfer has been confirmed in these Ir-based heterostructures, which plays an important role for facilitating HOR activity.…”

Bio‐inspired NiO/ZrO2 mixed oxides (NZMO) for oxygen evolution reactions: from facile synthesis to electrochemical analysis

“…The synthesis of durable and low‐cost materials for effective energy conversion and storage devices, such as batteries 13 and fuel cells, 9‐13 continues to be a major research challenge in the field of renewable energy. Fuel cells based on water electrolysis may efficiently convert chemical energy into electricity as green energy without releasing toxic pollutants into the atmosphere in contrast to fossil fuels 14‐17 . Water oxidation, however, necessitates a significant overpotential for multistep, four electrons and four protons, oxygen evolution events (OER) 18‐20 .…”

“…Water oxidation, however, necessitates a significant overpotential for multistep, four electrons and four protons, oxygen evolution events (OER) 18‐20 . Precious metals, such as ruthenium (Ru) and iridium (Ir) are considered to be the most efficient OER electrocatalysts, as these materials exhibit very low overpotentials and excellent stability response 14‐19,21 . However, their high cost and low availability are limiting their application for commercial level production of H 2 .…”

“…Fuel cells based on water electrolysis may efficiently convert chemical energy into electricity as green energy without releasing toxic pollutants into the atmosphere in contrast to fossil fuels. [14][15][16][17] Water oxidation, however, necessitates a significant overpotential for multistep, four electrons and four protons, oxygen evolution events (OER). [18][19][20] Precious metals, such as ruthenium (Ru) and iridium (Ir) are considered to be the most efficient OER electrocatalysts, as these materials exhibit very low overpotentials and excellent stability response.…”

“…[18][19][20] Precious metals, such as ruthenium (Ru) and iridium (Ir) are considered to be the most efficient OER electrocatalysts, as these materials exhibit very low overpotentials and excellent stability response. [14][15][16][17][18][19]21 However, their high cost and low availability are limiting their application for commercial level production of H 2 . As a result, substituting these precious-metal-free electrocatalysts with inexpensive and widely accessible transition metal-based electrocatalysts with equivalent activity and stability in an alkaline environment would be a significant step toward commercializing solar H 2 generators and electrolyzers.…”