Design of Noble Metal Electrocatalysts on an Atomic Level

Abstract

Nanostructured noble metal‐based materials have been considered in recent years as promising catalysts for energy storage and conversion. One of their prominent applications is a series of electrochemical processes in fuel cells, as they show excellent electrocatalytic performance towards the reactions occurring at both anode and cathode. Nowadays, considerable efforts have been devoted to boosting the catalytic activity and minimizing the used amount of precious metals. In this review, we introduce the recent advances regarding controllable synthesis of noble metal electrocatalysts at an atomic level. Important electrochemical reactions, such as oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), electroreduction of carbon dioxide (CO2) and so on, catalyzed by precisely controllable noble metal electrocatalysts will be highlighted. This review primarily focuses on the exploration for the relationship between atomic‐level structure of electrocatalysts and their enhanced catalytic property combining theoretical calculations and experiments. Finally, perspectives for further advances of noble metal nanomaterials are proposed to realize rational design of electrocatalysts at an atomic level.

Designing High‐Valence Metal Sites for Electrochemical Water Splitting

“…[ 3 ] Thus, the minimization of noble metal contents while still enhancing electrochemical properties and exhibiting high durability is a major challenge to be overcome for commercializing water electrolyzers. [ 7 ] Additionally, nonnoble metal‐based electrocatalysts have been widely studied, among which transition‐metal oxides (such as spinel and perovskite oxides), oxyhydroxides, alloys, transition‐metal phosphides, sulfides, carbides, and selenides have been confirmed as efficient earth‐abundant candidates for water splitting. [ 8 ] It has been reported that first‐row transition‐metal‐based compounds (e.g., (Ni, Co, Fe)‐based) have achieved OER catalytic activity values that are superior to those of noble metal oxides in alkaline solution.…”

“…[ 12 ] Highly oxidized redox couples, such as Fe 3+ /Fe 4+ , Co 3+ /Co 4+ , Ni 3+ /Ni 4+ , Mn 3+ /Mn 4+ , and Ir 4+ /Ir 6+ , are identified as active centers for the OER. [ 7,9e,13 ] For the pre‐catalysts of metal oxide with low‐valence sites, recent studies have demonstrated that surface reconstruction during the oxidative environment may be a necessary process for their enhanced electrocatalytic activity. [ 14 ] It was reported that the doping‐induced decreased valence states of metal sites facilitated the surface reconstruction with the generation of high‐valence active sites.…”

Rational Component and Structure Design of Noble‐Metal Composites for Optical and Catalytic Applications

“…Hu and co‐workers made important contributions to the UPD method. [ 151,157–159 ] An atomic Ru monolayer was deposited on ordered porous Pd octahedra by the UPD method. [ 157 ] Interestingly, by increasing the reaction temperature, the shape of this bimetallic noble‐metal nanostructure was transformed from a concave nanocube with a diameter of 15 nm to a 3D octahedral morphology with six hollow cavities (Figure 7d–f).…”

Electrocatalytic acidic oxygen evolution reaction: From nanocrystals to single atoms

“…[ 125 ] However, due to the tendency of metal ions to aggregate, proper synthesis methods are particularly important for the preparation of highly reactive SAC. [ 126,127 ]…”