Support Effects in Single-Atom Platinum Catalysts for Electrochemical Oxygen Reduction

Abstract

Single-atom catalysts (SACs) provide an ideal platform for reducing noble-metal usage. SACs also exhibit unusual catalytic properties due to the absence of a metal surface. The role of the support may have a significant effect on the catalytic properties, similar to that of the ligand molecules in homogeneous catalysts. Here, the support effect was demonstrated by preparing a single-atom platinum catalyst on two different supports: titanium carbide (Pt1/TiC) and titanium nitride (Pt1/TiN). The formation of single-atom Pt was confirmed by STEM, EXAFS, and in situ IR spectroscopy. Pt1/TiC showed higher activity, selectivity, and stability for electrochemical H2O2 production than Pt1/TiN. Density functional theory calculations presented that oxygen species have strong affinity into Pt1/TiN, possibly acting as surface poisoning species, and Pt1/TiC preserves oxygen–oxygen bonds more with higher selectivity toward H2O2 production. This work clearly shows that the support in SACs actively participates in the surface reaction and does not just act as anchoring sites for single atoms.

General π‐Electron‐Assisted Strategy for Ir, Pt, Ru, Pd, Fe, Ni Single‐Atom Electrocatalysts with Bifunctional Active Sites for Highly Efficient Water Splitting

“…[1,2] Multifarious single atoms have been fabricated and demonstrated their ultimate size effects,s uch as Co 1 , [3] Pt 1 , [4] Ru 1 , [5] Ir 1 , [6] Fe 1 , [7] and Pd 1 . [11] It is believed that the strong metal-support interactions (SMSI) can change the physics of the orbitals,b and gap,e lectron density,a nd surface chemistry of the SACs,s ot hat they exhibit different catalytic properties for aw ide variety of chemical reactions.Onthe other hand, electrochemical water splitting is regarded as the most efficient and clean technology for high-purity hydrogen generation. [11] It is believed that the strong metal-support interactions (SMSI) can change the physics of the orbitals,b and gap,e lectron density,a nd surface chemistry of the SACs,s ot hat they exhibit different catalytic properties for aw ide variety of chemical reactions.Onthe other hand, electrochemical water splitting is regarded as the most efficient and clean technology for high-purity hydrogen generation.…”

A General Method for Transition Metal Single Atoms Anchored on Honeycomb‐Like Nitrogen‐Doped Carbon Nanosheets

“…Several reports demonstrated the successful preparation of Pt‐based SACs for the ORR catalysis. Unfortunately, the reduction of O 2 is prone to produce H 2 O 2 via two‐electron process instead of four‐electron pathway in the presence of Pt‐based SACs, which is detrimental for fuel cells. Therefore, developing nonnoble metal SACs with low cost and high efficiency has been the hotspot.…”

Highly Durable Platinum Single‐Atom Alloy Catalyst for Electrochemical Reactions

“…[4] We also reported that single atomic Pt supported on TiN and TiC showed high selectivity to the production of H 2 O 2 in the electrocatalytic oxygen reduction reaction (ORR). [3,5] However, although the atomically dispersed catalysts have shown great potential for various heterogeneous reactions, there are still issues to be solved. They have been usually prepared with very low loadings, <1 wt%, and their durability is often poor due to intrinsically unstable nature of the single atomic structure.…”

“…[1,6] For this reason, single metal atoms have to be stabilized on supports such as metal oxides/carbides/ nitrides, [4,5,7] graphene, [8,9] zeolites, [10] or single crystalline metals. [11,12] For electrochemical applications, the support should be conductive.…”