Colloidal Nanocrystals as Electrocatalysts with Tunable Activity and Selectivity

Abstract

Correlating the catalyst activity, selectivity, and stability with its structure and composition is of the utmost importance in advancing the knowledge of heterogeneous electrocatalytic processes for chemical energy conversion. Well-defined colloidal nanocrystals with tunable monodisperse size and uniform shapes are ideal platforms to investigate the effect of these parameters on the catalytic performance. In addition to translating the knowledge from single-crystal studies to more realistic conditions, the morphological and compositional complexity attainable by colloidal chemistry can provide access to active catalysts which cannot be produced by other synthetic approaches. The sample uniformity is also beneficial to investigate catalyst reconstruction processes via both ex situ and operando techniques. Finally, colloidal nanocrystals are obtained as inks, a feature which facilitates their integration on different substrates and cell configurations to study the impact of interactions at the mesoscale and the device-dependent reaction microenvironment on the catalytic outcome. In this Review, we discuss recent studies in selected electrochemical reactions and provide our outlook on future developments on the use of well-defined colloidal nanocrystals as an emerging class of electrocatalysts.

Noble Metal‐Based Multimetallic Nanoparticles for Electrocatalytic Applications

“…[16] Besides, the support materials can also affect the catalytic properties of nanoparticles through metal-support interactions, [17] and the stability of supports becomes significant, especially when the operating conditions are harsh or long-term operation is required. [3] In this review, recent developments in the synthesis of NMMNs, which are categorized based on their structural features (Figure 1), are highlighted. For each structure, representative synthetic methods with exemplary works are provided.…”

“…[ 1 ] It is widely accepted that noble metals (mainly Pt, Pd, Ir, Rh, Ru, and Au) have great potential as electrocatalysts due to their optimal sorption properties in volcano‐shaped activity trends for many representative electrocatalytic reactions that comprise fuel cells, water splitting, and CO 2 electrolysis. [ 2 , 3 ] These metals are usually utilized in various forms of nanoparticles to take advantage of their maximized surface area and defect‐rich surfaces. The surface properties are well known to strongly influence the overall catalytic performance of noble metal nanoparticles.…”

“…As the ligands can either have (usually) detrimental or (rarely) promotive effects on electrocatalytic processes, it is essential to consider them for better utilization of NMMNs. [ 3 , 15 ] On the other hand, catalytically active nanoparticles are usually anchored on the surface of support materials before being applied in catalytic reactions to prevent the agglomeration of nanoparticles and also to ensure sufficient electrical conductivity. [ 16 ] Besides, the support materials can also affect the catalytic properties of nanoparticles through metal‐support interactions, [ 17 ] and the stability of supports becomes significant, especially when the operating conditions are harsh or long‐term operation is required.…”

“…[ 16 ] Besides, the support materials can also affect the catalytic properties of nanoparticles through metal‐support interactions, [ 17 ] and the stability of supports becomes significant, especially when the operating conditions are harsh or long‐term operation is required. [ 3 ]…”

Surfactant-Free Precious Metal Colloidal Nanoparticles for Catalysis

“…Colloidal syntheses have been a key tool to advance the field of catalysis (Guntern et al, 2021;Losch et al, 2019) and strategies to overcome the above drawbacks have been reported. For heterogeneous catalytic applications and electrocatalysis, the NPs are typically supported on another material.…”