Noble metal binary alloy nanoframes have emerged as a new class of fuel cell electrocatalysts because of their intrinsic high catalytic surface area and accompanied high catalytic activity. However, their inferior structural and compositional stability during catalysis pose as formidable huddles to their practical applications. Herein, it is reported that introduction of an additional component to the binary catalytic system may serve as a simple and effective means of enhancing the structural and compositional stability of nanoframe‐based electrocatalysts. It is demonstrated that in situ doping of Co to the PtCu alloy nanoframe yields a ternary PtCuCo rhombic dodecahedral nanoframe (Co‐PtCu RNF) with a reinforced vertex structure. Co‐PtCu RNF exhibits superior electrocatalytic activity and durability for the oxygen reduction reaction to those of PtCu rhombic dodecahedral nanoframe (PtCu RNF) and Pt/C catalysts, due to its ternary composition and vertex‐strengthened frame structure. Furthermore, Co‐PtCu RNF shows enhanced activity for the methanol oxidation reaction as compared to PtCu RNF and Pt/C.

Nanoframe alloy structures represent a class of high-performance catalysts for the oxygen reduction reaction (ORR), owing to their high active surface area, efficient molecular accessibility, and nanoconfinement effect. However, structural and chemical instabilities of nanoframes remain an important challenge. Here, we report the synthesis of PtCu nanoframes constructed with an atomically ordered intermetallic structure (O-PtCuNF/C) showing high ORR activity, durability, and chemical stability. We rationally designed the O-PtCuNF/C catalyst by combining theoretical composition predictions with a silicacoating-mediated synthesis. The O-PtCuNF/C combines intensified strain and ligand effects from the intermetallic PtCu L1 1 structure and advantages of the nanoframes, resulting in superior ORR activity to disordered alloy PtCu nanoframes (D-PtCuNF/C) and commercial Pt/C catalysts. Importantly, the O-PtCuNF/C showed the highest ORR mass activity among PtCu-based catalysts. Furthermore, the O-PtCuNF/C exhibited higher ORR durability and far less etching of constituent atoms than D-PtCuNF/C and Pt/C, attesting to the chemically stable nature of the intermetallic structure.

This article reviews recent advances in the synthetic strategies for metal/metal compound hetero-interfaces within a nanostructure and their beneficial synergistic effect on the electrocatalytic performance toward energy conversion applications such as the HER, OER and ORR.

The ever‐increasing need for the production and expenditure of sustainable energy is a result of the astonishing rate of consumption of fossil fuels and the accompanying environmental problems. Emphasis is being directed to the generation of sustainable energy by the fuel cell and water splitting technologies. Accordingly, the development of highly efficient electrocatalysts has attracted significant interest, as the fuel cell and water splitting technologies are critically dependent on their performance. Among numerous catalyst designs under investigation, nanoframe catalysts have an intrinsically large surface area per volume and a tunable composition, which impacts the number of catalytically active sites and their intrinsic catalytic activity, respectively. Nevertheless, the structural integrity of the nanoframe during electrochemical operation is an ongoing concern. Some significant advances in the field of nanoframe catalysts have been recently accomplished, specifically geared to resolving the catalytic stability concerns and significantly boosting the intrinsic catalytic activity of the active sites. Herein, general synthetic concepts of nanoframe structures and their structure‐dependent catalytic performance are summarized, along with recent notable advances in this field. A discussion on the remaining challenges and future directions, addressing the limitations of nanoframe catalysts, are also provided.

Designing an efficient and durable electrocatalyst for the sluggish oxygen evolution reaction (OER) at the anode remains the foremost challenge in developing proton exchange membrane (PEM) electrolyzers. Here, a highly active and durable cactus‐like nanoparticle with an exposed heterointerface between the IrO2 and the low oxidation state Ru by introducing a trace amount of Mn dopant is reported. The heterostructure fabrication relies on initial mixing of the Ru and Ir phases before electrochemical oxidation to produce a conjoined Ru/IrO2 heterointerface. Benefitting from electron transfer at the heterointerface, the low oxidation state Ru species shows excellent initial activity, which is maintained even after 180 h of continuous OER test. In a half‐cell test, the Mn‐doped RuIr nanocactus (Mn‐RuIr NCT) achieves a mass activity of 1.85 A mgIr+Ru−1 at 1.48 VRHE, which is 139‐fold higher than that of commercial IrO2. Moreover, the superior electrocatalytic performance of Mn‐RuIr NCT in the PEM electrolysis system ensures its viability in practical uses. The results of the excellent catalytic performance for acidic OER indicate that the heterostructuring robust rutile IrO2 and the highly active Ru species with a low oxidation state on the catalyst surface drive a synergistic effect.

The oxygen evolution reaction (OER) requires a large overpotential which undermines the stability of electrocatalysts, typically IrOx or RuOx. RuOx is particularly vulnerable to high overpotential in acidic media, due...

L10-PtZn intermetallic nanoparticles embedded in hollow, N-doped carbon nanocages were directly synthesized from the solid-state precursor, Pt2+-exchanged ZIF-8 nanocubes.

Copper‐based catalysts have attracted enormous attention due to their high selectivity for C2+ products during the electrochemical reduction of CO2 (CO2RR). In particular, grain boundaries on the catalysts contribute to the generation of various Cu coordination environments, which have been found essential for C—C coupling. However, smooth‐surfaced Cu2O nanocrystals generally lack the ability for the surface reorganization to form multiple grain boundaries and desired Cu undercoordination sites. Flow chemistry armed with the unparalleled ability to mix reaction mixture can achieve a very high concentration of unstable reaction intermediates, which in turn are used up rapidly to lead to kinetics‐driven nanocrystal growth. Herein, the synthesis of a unique hierarchical structure of Cu2O with numerous steps (h‐Cu2O ONS) via flow chemistry‐assisted modulation of nanocrystal growth kinetics is reported. The surface of h‐Cu2O ONS underwent rapid surface reconstruction under CO2RR conditions to exhibit multiple heterointerfaces between Cu2O and Cu phases, setting the preferable condition to facilitate C—C bond formation. Notably, the h‐Cu2O ONS obtained the increased C2H4 Faradaic efficiency from 31.9% to 43.5% during electrocatalysis concurrent with the morphological reorganization, showing the role of the stepped surface. Also, the h‐Cu2O ONS demonstrated a 3.8‐fold higher ethylene production rate as compared to the Cu2O nanocube.