Molecular Trapping Strategy To Stabilize Subnanometric Pt Clusters for Highly Active Electrocatalysis

Abstract

Structure engineering is an effective way to substantially adjust the chemical and physical properties of materials. However, the effects of structure engineering of carbon hosts on the catalytic properties of Pt-based catalysts at the molecular scale are poorly understood. Herein, we report a molecular-level strategy to anchor and stabilize subnanometric Pt clusters on a covalently coupled host of graphitic carbon nitride (g-C3N4) and carbon nanotubes (CNT) for the development of electrocatalysts with high activities toward methanol oxidation reactions. Theoretical evaluation and experimental validation identified that the chemical integration of g-C3N4 on CNT is critical in optimizing the electronic structures and catalytic properties of Pt catalysts. As a result, the Pt-g-C3N4-CNT possesses a high energy level of d-band position, significantly strengthening its adsorption behaviors for the key reaction intermediates during the methanol electrooxidation process and energetically decreasing the energy barriers in the multistep reaction pathways. Combining with the strong catalyst–support interactions afforded by the adaptive coordination environment of g-C3N4 with Pt clusters as well as the unimpeded electron transfer via a σ-orbital overlap between CNTs and g-C3N4, the as-obtained Pt-g-C3N4-CNT possesses prodigious electrocatalytic properties including high activities, unusual poison tolerance, and reliable long-term discharge stabilities toward methanol oxidation reactions, in comparison to commercial Pt/activated carbon (Pt-AC) and Pt-CNT catalysts. This molecular-level finding opens up a new avenue to design and develop more efficient and effective carbon-based supports for fabricating advanced heterogeneous catalysts and could also be extended to more applications, such as lithium-ion batteries, lithium-sulfur batteries, supercapacitors, and sensors.

Descriptors for the Evaluation of Electrocatalytic Reactions: d‐Band Theory and Beyond

“…Reproduced with permission. [ 202 ] Copyright 2019, American Chemical Society. g) X‐ray photoelectron spectroscopy (XPS) Au 4f.…”

“…Pt (Upshift of ε d ) : By anchoring Pt clusters on a covalently coupled support of g‐C 3 N 4 and carbon nanotubes, Chen et al have successfully realized the upshift of the d‐band center of Pt and thus strengthen the binding ability of the key intermediates to the electrocatalysts (Figure 19e). [ 202 ] The electrochemical performance of the electrocatalysts toward methanol oxidation has been comprehensively investigated. As expected, the Pt‐g‐C 3 N 4 ‐CNT shows the highest methanol oxidation current density of 19.45 mA cm –2 , which is much higher than those counterparts and the recently reported state‐of‐art electrocatalysts (Figure 19f).…”

Modulating Electronic Structure of an Au‐Nanorod‐Core–PdPt‐Alloy‐Shell Catalyst for Efficient Alcohol Electro‐Oxidation

“…Among reported noble-based catalysts, those based on the Pt metal are regarded as the star electrocatalysts for the AORs in terms of their oxidation overpotentials and Tafel slopes. [12,13] Notably, their alloys with other metals (e.g., Ru, Ni, Co, Pd, Rh, and Au) exhibit strong adsorption capability toward OH species or a so-called bifunctional mechanism, leading to improved AOR performance. [14][15][16][17] On the other hand, the serious poisoning effect of the carbonaceous intermediates (especially CO) hinders dramatically the activity of the used catalysts (especially the Pt catalysts) and eventually leads to much reduced conversion efficiencies of the AORs.…”

The Pt/g-C3N4-CNS catalyst via in situ synthesis process with excellent performance for methanol electrocatalytic oxidation reaction

“…The energy barrier in the multi-step reaction path is reduced in energy. 28 They all used melamine or urea and other precursors for the in situ doping of g-C 3 N 4 into the catalyst support and found that the stability and catalytic activity of the catalyst were greatly improved. Some researchers [29][30][31] prepared composite carriers by mechanical mixing.…”