Nanoporous PdNi Bimetallic Catalyst with Enhanced Electrocatalytic Performances for Electro‐oxidation and Oxygen Reduction Reactions

A nanoporous PdNi (np‐PdNi) bimetallic catalyst fabricated by electrochemically dealloying a Pd₂₀Ni₈₀ alloy in an acid solution is reported. Residual Ni in the nanoporous alloy can be controlled by tuning dealloying potentials and the electrocatalysis of the np‐PdNi shows evident dependence on Ni concentrations. With ～9 at.% Ni, the np‐PdNi bimetallic catalyst presents superior electrocatalytic performances in methanol and formic acid electro‐oxidation as well as oxygen reduction in comparison with commercial Pd/C and nanoporous Pd (np‐Pd). The excellent electrocatalytic properties of the dealloyed np‐PdNi bimetallic catalyst appear to arise from the combined effect of unique bicontinuous nanoporosity and bimetallic synergistic action.     

A Core‐Shell Nanoporous Pt‐Cu Catalyst with Tunable Composition and High Catalytic Activity

Composition‐controlled fabrication of bimetallic catalysts is of significance in electrochemical energy conversion and storage. A novel nanoporous Pt‐Cu bimetallic catalyst with a Pt skin and a Pt‐Cu core, fabricated by electrochemically dealloying a bulk Pt‐Cu binary alloy using a potential‐controlled approach, is reported. The Pt/Cu ratio of the dealloyed nanoporous catalyst can be readily adjusted in a wide composition range by only controlling dealloying potential. The electro‐catalytic performance of the nanoporous Pt‐Cu catalyst shows evident dependence on Pt/Cu ratio although the surfaces of all the nanoporous catalysts are characterized to be covered by pure Pt. With optimal compositions, the dealloyed nanoporous Pt‐Cu catalyst possesses enhanced electrocatalytic activities toward oxygen reduction reaction and formic acid oxidation in comparison with the commercial Pt/C catalyst.     

Platinum‐Coated Hollow Graphene Nanocages as Cathode Used in Lithium‐Oxygen Batteries

One of the formidable challenges facing aprotic lithium‐oxygen (Li‐O₂) batteries is the high charge overpotential, which induces the formation of byproducts, loss in efficiency, and poor cycling performance. Herein, the synthesis of the ultrasmall Pt‐coated hollow graphene nanocages as cathode in Li‐O₂ batteries is reported. The charge voltage plateau can reduce to 3.2 V at the current density of 100 mA g^?1, even maintain below 3.5 V when the current density increased to 500 mA g^?1. The unique hollow graphene nanocages matrix can not only provide numerous nanoscale tri‐phase regions as active sites for efficient oxygen reduction, but also offer sufficient amount of mesoscale pores for rapid oxygen diffusion. Furthermore, with strong atomic‐level oxygen absorption into its subsurface, ultrasmall Pt catalytically serves as the nucleation site for Li₂O₂ growth. The Li₂O₂ is subsequently induced into a favorable form with small size and amorphous state, decomposed more easily during recharge. Meanwhile, the conductive hollow graphene substrate can enhance the catalytic activity of noble metal Pt catalysts due to the graphene‐metal interfacial interaction. Benefiting from the above synergistic effects between the hollow graphene nanocages and the nanosized Pt catalysts, the ultrasmall Pt‐decorated graphene nanocage cathode exhibits enhanced electrochemical performances.     

MO‐Co@N‐Doped Carbon (M = Zn or Co): Vital Roles of Inactive Zn and Highly Efficient Activity toward Oxygen Reduction/Evolution Reactions for Rechargeable Zn–Air Battery

A highly efficient bifunctional oxygen catalyst is required for practical applications of fuel cells and metal–air batteries, as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are their core electrode reactions. Here, the MO‐Co@N‐doped carbon (NC, M = Zn or Co) is developed as a highly active ORR/OER bifunctional catalyst via pyrolysis of a bimetal metal–organic framework containing Zn and Co, i.e., precursor (CoZn). The vital roles of inactive Zn in developing highly active bifunctional oxygen catalysts are unraveled. When the precursors include Zn, the surface contents of pyridinic N for ORR and the surface contents of Co–N_x and Co³⁺/Co²⁺ ratios for OER are enhanced, while the high specific surface areas, high porosity, and high electrochemical active surface areas are also achieved. Furthermore, the synergistic effects between Zn‐based and Co‐based species can promote the well growth of multiwalled carbon nanotubes (MWCNTs) at high pyrolysis temperatures (≥700 °C), which is favorable for charge transfer. The optimized CoZn‐NC‐700 shows the highly bifunctional ORR/OER activity and the excellent durability during the ORR/OER processes, even better than 20 wt% Pt/C (for ORR) and IrO₂ (for OER). CoZn‐NC‐700 also exhibits the prominent Zn–air battery performance and even outperforms the mixture of 20 wt% Pt/C and IrO₂.     

From 3D ZIF Nanocrystals to Co–Nx/C Nanorod Array Electrocatalysts for ORR,OER, and Zn–Air Batteries

Designing a highly active electrocatalyst with optimal stability at low cost is must and non‐negotiable if large‐scale implementations of fuel cells are to be fully realized. Zeolitic‐imidazolate frameworks (ZIFs) offer rich platforms to design multifunctional materials due to their flexibility and ultrahigh surface area. Herein, an advanced Co–N_x/C nanorod array derived from 3D ZIF nanocrystals with superior electrocatalytic activity and stability toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) compared to commercial Pt/C and IrO₂, respectively, is synthesized. Remarkably, as a bifunctional catalyst (E_{j = 10} (OER) ? E_1/2 (ORR) ≈ 0.65 V), it further displays high performance of Zn–air batteries with high cycling stability even at a high current density. Such supercatalytic properties are largely attributed to the synergistic effect of the chemical composition, high surface area, and abundant active sites of the nanorods. The activity origin is clarified through post oxygen reduction X‐ray photoelectron spectroscopy analysis and density functional theory studies. Undoubtedly, this approach opens a new avenue to strategically design highly active and performance‐oriented electrocatalytic materials for wider electrochemical energy applications.     

A General Carboxylate-Assisted Approach to Boost the ORR Performance of ZIF-Derived Fe/N/C Catalysts for Proton Exchange Membrane Fuel Cells

An Fe/N/C catalyst derived from the pyrolysis of metal–organic frameworks, for example, a zeolitic-imidazolate-framework-8 (ZIF-8), has been regarded as one of the most promising non-precious metal catalysts toward oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). However, its ORR mass activity is still much inferior to that of Pt, partly because of the lack of general and efficient synthetic strategies. Herein, a general carboxylate-assisted strategy that dramatically enhances the ORR mass activity of ZIF-derived Fe/N/C catalysts is reported. The carboxylate is found to promote the formation of Fe/N/C catalysts with denser accessible active sites and entangled carbon nanotubes, as well as a higher mesoporosity. These structural advantages make the carboxylate-assisted Fe/N/C catalysts show a 2–10 fold higher ORR mass activity than the common carboxylate-free one in various cases. When applied in H₂–O₂ PEMFCs, the active acetate-assisted Fe/N/C catalyst generates a peak power density of 1.33 W cm⁻², a new record of peak power density for a H₂–O₂ PEMFC with non-Pt ORR catalysts.     

Ordered Porous Electrodes by Design: Toward Enhancing the Effective Utilization of Platinum in Electrocatalysis

Platinum‐nanoparticle‐functionalized, ordered, porous support electrodes are prepared and characterized as a potential new class of oxygen reduction reaction (ORR) electrocatalysts. This study aims to develop electrode materials that enhance the effective utilization of Pt in electrocatalytic reactions through improved mass transport properties, high Pt mass specific surface area, and increased Pt electrochemical stability. The electrodes are prepared using modular sacrificial templates, producing a uniform distribution of Pt nanoparticles inside ordered porous Au electrodes. This method can be further fine‐tuned to optimize the architecture for a range of characteristics, such as varying nanoparticle properties, pore size, or support material. The Pt‐coated Au, ordered, porous electrodes exhibit several improved characteristics, such as enhanced Pt effective utilization for ORR electrocatalysis. This includes a nearly twofold increase in Pt mass specific surface area over other ultrathin designs, superior mass transport properties in comparison to traditional catalyst layers of C black supported Pt nanoparticles mixed with ionomer, good methanol tolerance and exceptional stability toward Pt chemical and/or electrochemical dissolution through interfacial interactions with Au. The methods to prepare Pt‐coated ordered porous electrodes can be extended to other architectures for enhanced catalyst utilization and improved performance of Pt in electrochemical processes.     

Nitrogen‐Doped Nanoporous Carbon/Graphene Nano‐Sandwiches: Synthesis and Application for Efficient Oxygen Reduction

A zeolitic‐imidazolate‐framework (ZIF) nanocrystal layer‐protected carbonization route is developed to prepare N‐doped nanoporous carbon/graphene nano‐sandwiches. The ZIF/graphene oxide/ZIF sandwich‐like structure with ultrasmall ZIF nanocrystals (i.e., ≈20 nm) fully covering the graphene oxide (GO) is prepared via a homogenous nucleation followed by a uniform deposition and confined growth process. The uniform coating of ZIF nanocrystals on the GO layer can effectively inhibit the agglomeration of GO during high‐temperature treatment (800 °C). After carbonization and acid etching, N‐doped nanoporous carbon/graphene nanosheets are formed, with a high specific surface area (1170 m² g^?1). These N‐doped nanoporous carbon/graphene nanosheets are used as the nonprecious metal electrocatalysts for oxygen reduction and exhibit a high onset potential (0.92 V vs reversible hydrogen electrode; RHE) and a large limiting current density (5.2 mA cm^?2 at 0.60 V). To further increase the oxygen reduction performance, nanoporous Co‐N_x/carbon nanosheets are also prepared by using cobalt nitrate and zinc nitrate as cometal sources, which reveal higher onset potential (0.96 V) than both commercial Pt/C (0.94 V) and N‐doped nanoporous carbon/graphene nanosheets. Such nanoporous Co‐N_x/carbon nanosheets also exhibit good performance such as high activity, stability, and methanol tolerance in acidic media.     

Flexible Solid-State Direct Ethanol Fuel Cell Catalyzed by Nanoporous High-Entropy Al-Pd-Ni-Cu-Mo Anode and Spinel (AlMnCo)3O4 Cathode

As in many other electrochemical energy-converting systems, the flexible direct ethanol fuel cells rely heavily on high-performance catalysts with low noble metal contents and high tolerance to poisoning. In this work, a generic dealloying procedure to synthesize nanoporous multicomponent anodic and cathodic catalysts for the high-performance ethanol fuel cells is reported. On the anode side, the nanoporous AlPdNiCuMo high-entropy alloy exhibits an electrochemically active surface area of 88.53 m² g⁻¹_Pd and a mass activity of 2.67 A mg⁻¹_Pd for the ethanol oxidation reaction. On the cathode side, the dealloyed spinel (AlMnCo)₃O₄ nanosheets with no noble metals demonstrate a comparable catalytic performance as the standard Pt/C for the oxygen reduction reaction, and tolerance to high concentrations of ethanol. Equipped with such anodic and cathodic catalysts, the flexible solid-state ethanol fuel cell is able to deliver an ultra-high energy density of 13.63 mWh cm⁻² with only 3 mL ethanol, which is outstanding compared with other similar solid-state energy devices. Moreover, the solid-state ethanol fuel cell is highly flexible, durable and exhibits an inject-and-run function.     

Searching General Sufficient‐and‐Necessary Conditions for Ultrafast Hydrogen‐Evolving Electrocatalysis

The development of cost‐effective and high‐performance electrocatalysts for the hydrogen evolution reaction (HER) is one critical step toward successful transition into a sustainable green energy era. Different from previous design strategies based on single parameter, here the necessary and sufficient conditions are proposed to develop bulk non‐noble metal oxides which are generally considered inactive toward HER in alkaline solutions: i) multiple active sites for different reaction intermediates and ii) a short reaction path created by ordered distribution and appropriate numbers of these active sites. Computational studies predict that a synergistic interplay between the ordered oxygen vacancies (at pyramidal high‐spin Co³⁺ sites) and the O 2p ligand holes (OLH; at metallic octahedral intermediate‐spin Co⁴⁺ sites) in RBaCo₂O_5.5+δ (δ = 1/4; R = lanthanides) can produce a near‐ideal HER reaction path to adsorb H₂O and release H₂, respectively. Experimentally, the as‐synthesized (Gd_0.5La_0.5)BaCo₂O_5.75 outperforms the state‐of‐the‐art Pt/C catalyst in many aspects. The proof‐of‐concept results reveal that the simultaneous possession of ordered oxygen vacancies and an appropriate number of OLH can realize a near‐optimal synergistic catalytic effect, which is pivotal for rational design of oxygen‐containing materials.     

The Quasi‐Pt‐Allotrope Catalyst: Hollow PtCo@single‐Atom Pt1 on Nitrogen‐Doped Carbon toward Superior Oxygen Reduction

Single‐atom Pt and bimetallic Pt₃Co are considered the most promising oxygen reduction reaction (ORR) catalysts, with a much lower price than pure Pt. The combination of single‐atom Pt and bimetallic Pt₃Co in a highly active nanomaterial, however, is challenging and vulnerable to agglomeration under realistic reaction conditions, leading to a rapid fall in the ORR. Here, a sustainable quasi‐Pt‐allotrope catalyst, composed of hollow Pt₃Co (H‐PtCo) alloy cores and N‐doped carbon anchoring single atom Pt shells (Pt₁N‐C), is constructed. This unique nanoarchitecture enables the inner and exterior spaces to be easily accessible, exposing an extra‐high active surface area and active sites for the penetration of both aqueous and organic electrolytes. Moreover, the novel Pt₁N‐C shells not only effectively protect the H‐PtCo cores from agglomeration but also increase the efficiency of the ORR in virtue of the isolated Pt atoms. Thus, the H‐PtCo@Pt₁N‐C catalyst exhibits stable ORR without any fade over a prolonged 10 000 cycle test at 0.9 V in HClO₄ solution. Furthermore, this material can offer efficient and stable ORR activities in various organic electrolytes, indicating its great potential for next‐generation lithium–air batteries as well.     

Evolution of Nanoporous Pt–Fe Alloy Nanowires by Dealloying and their Catalytic Property for Oxygen Reduction Reaction

The short life and high cost of carbon‐supported Pt nanoparticle catalysts (Pt/C) are two main problems with proton exchange membrane fuel cells. Porous Pt alloy nanowires have more durability and catalytic activity than Pt/C. Dealloying is a facile way to make nanoporous Pt. However, the process of porosity formation is difficult to control. In this paper, electrospinning and chemical dealloying techniques are used to make long, thin and yet nanoporous Pt–Fe alloy nanowires. The evolution of nanoporosity is observed and studied. It is found that non‐uniform composition in the precursor PtFe₅ alloy nanowires helps the formation of nanoporous structure. The overall wire diameter is about 10–20 nm and the ligament diameter only 2–3 nm. These porous long nanowires interweave to form a self‐supporting network with a high specific activity, 2.3 times that of conventional Pt/C catalysts, and also have better durability.     

Hybrid of Iron Nitride and Nitrogen‐Doped Graphene Aerogel as Synergistic Catalyst for Oxygen Reduction Reaction

It is extremely desirable but challenging to create highly active, stable, and low‐cost catalysts towards oxygen reduction reaction to replace Pt‐based catalysts in order to perform the commercialization of fuel cells. Here, a novel iron nitride/nitrogen doped‐graphene aerogel hybrid, synthesized by a facile two‐step hydrothermal process, in which iron phthalocyanine is uniformly dispersed and anchored on graphene surface with the assist of π–π stacking and oxygen‐containing functional groups, is reported. As a result, there exist strong interactions between Fe _x N nanoparticles and graphene substrates, leading to a synergistic effect towards oxygen reduction reaction. It is worth noting that the onset potential and current density of the hybrid are significantly better and the charge transfer resistance is much lower than that of pure nitrogen‐doped graphene aerogel, free Fe _x N and their physical mixtures. The hybrid also exhibits comparable catalytic activity as commercial Pt/C at the same catalyst loading, while its stability and resistance to methanol crossover are superior. Interestingly, it is found that, apart from the active nature of the hybrid, the large surface area and porosity are responsible for its excellent onset potential and the high density of Fe–N–C sties and small size of Fe _x N particles boost charge transfer rate.     

Platinum Porous Nanosheets with High Surface Distortion and Pt Utilization for Enhanced Oxygen Reduction Catalysis

Unlike the well‐established shape/composition control, surface distortion is a newly emerged yet largely unexplored nanosurface engineering for boosting electrocatalysis. Tapping into the novel electrocatalysts for taking full use of the distortion effect is therefore of importance but remains a formidable challenge. Here, an approach to designing highly distorted porous Pt nanosheets (NSs) by electrochemical erosion of ultrathin PtTe₂ NSs is reported. The inherent ultrathin feature and massive leaching of Te have conspired to produce a highly distorted structure. As a result, the generated Pt NSs exhibit a much‐enhanced oxygen reduction reaction (ORR) mass and specific activity of 2.07 A mg_Pt^?1 and 3.1 mA cm^?2 at 0.90 V versus reversible hydrogen electrode, 9.8 and 10.7 times higher than those of commercial Pt/C. The highly distorted Pt NSs can endure 30 000 cycles with negligible activity decay and structure variation. Density functional theory calculations reveal that the electrochemical corrosion induced nanopores, boundaries, and vacancies consist of Pt sites with substantially low coordination numbers deviating from the one of pristine Pt (111) surface. These Pt sites actively act as electron‐depleting centers for highly efficient electron transfer toward the adsorbing O‐species. This study opens a new design for fully using the distortion effect to promote ORR performance and beyond.     

Controlled Fabrication of Hierarchically Structured Nitrogen‐Doped Carbon Nanotubes as a Highly Active Bifunctional Oxygen Electrocatalyst

Hierarchically structured nitrogen‐doped carbon nanotube (NCNT) composites, with copper (Cu) nanoparticles embedded uniformly within the nanotube walls and cobalt oxide (Co_xO_y) nanoparticles decorated on the nanotube surfaces, are fabricated via a combinational process. This process involves the growth of Cu embedded CNTs by low‐ and high‐temperature chemical vapor deposition, post‐treatment with ammonia for nitrogen doping of these CNTs, precipitation‐assisted separation of NCNTs from cobalt nitrate aqueous solution, and finally thermal annealing for Co_xO_y decoration. Theoretical calculations show that interaction of Cu nanoparticles with CNT walls can effectively decrease the work function of CNT surfaces and improve adsorption of hydroxyl ions onto the CNT surfaces. Thus, the activities of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are significantly enhanced. Because of this benefit, further nitrogen doping, and synergistic coupling between Co_xO_y and NCNTs, Cu@NCNT/Co_xO_y composites exhibit ORR activity comparable to that of commercial Pt/C catalysts and high OER activity (outperforming that of IrO₂ catalysts). More importantly, the composites display superior long‐term stability for both ORR and OER. This simple but general synthesis protocol can be extended to design and synthesis of other metal/metal oxide systems for fabrication of high‐performance carbon‐based electrocatalysts with multifunctional catalytic activities.     

Synergistically Enhanced Oxygen Reduction Electrocatalysis by Subsurface Atoms in Ternary PdCuNi Alloy Catalysts

For Pd‐based alloy catalysts, the selection of metallic alloying elements and the construction of composition‐gradient surface and subsurface layers are critical in achieving superior electrocatalytic activities in, e.g., the oxygen reduction reaction (ORR). Based on the Pd‐containing alloy, highly monodispersed PdCuNi ternary alloy nanocrystals are prepared through a wet‐chemical approach, and a solution‐based oxidative surface treatment protocol is utilized to activate the surface of the nanocrystals. A drastically enhanced ORR activity can be achieved by removing the surface Ni and Cu atoms through the surface treatment protocol. The treated catalyst demonstrates a mass activity of 0.45 A mg_Pd^?1 in alkaline medium, 5 and 2.4 times those of commercial Pt/C and Pd/C, respectively. The first‐principle calculation result suggests the critical roles of the coexistence of Ni and Cu atoms and their synergistic interaction beneath the outmost pure Pd layer in optimizing the oxygen binding energy for ORR. The calculation also suggests that the optimal binding energy of oxygen requires an appropriate Ni/Cu ratio in the subsurface layer. This work demonstrates a class of high‐performance Pt‐free ternary alloy ORR catalysts and may provide a general guideline for the structural design of Pd‐based ternary alloy catalysts.     

Nanoporous Nitrogen‐Doped Graphene Oxide/Nickel Sulfide Composite Sheets Derived from a Metal‐Organic Framework as an Efficient Electrocatalyst for Hydrogen and Oxygen Evolution

Engineering of controlled hybrid nanocomposites creates one of the most exciting applications in the fields of energy materials and environmental science. The rational design and in situ synthesis of hierarchical porous nanocomposite sheets of nitrogen‐doped graphene oxide (NGO) and nickel sulfide (Ni₇S₆) derived from a hybrid of a well‐known nickel‐based metal‐organic framework (NiMOF‐74) using thiourea as a sulfur source are reported here. The nanoporous NGO/MOF composite is prepared through a solvothermal process in which Ni(II) metal centers of the MOF structure are chelated with nitrogen and oxygen functional groups of NGO. NGO/Ni₇S₆ exhibits bifunctional activity, capable of catalyzing both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with excellent stability in alkaline electrolytes, due to its high surface area, high pore volume, and tailored reaction interface enabling the availability of active nickel sites, mass transport, and gas release. Depending on the nitrogen doping level, the properties of graphene oxide can be tuned toward, e.g., enhanced stability of the composite compared to commonly used RuO₂ under OER conditions. Hence, this work opens the door for the development of effective OER/HER electrocatalysts based on hierarchical porous graphene oxide composites with metal chalcogenides, which may replace expensive commercial catalysts such as RuO₂ and IrO₂.     

Facile Synthesis of Manganese‐Oxide‐Containing Mesoporous Nitrogen‐Doped Carbon for Efficient Oxygen Reduction

Developing low‐cost non‐precious metal catalysts for high‐performance oxygen reduction reaction (ORR) is highly desirable. Here a facile, in situ template synthesis of a MnO‐containing mesoporous nitrogen‐doped carbon (m‐N‐C) nanocomposite and its high electrocatalytic activity for a four‐electron ORR in alkaline solution are reported. The synthesis of the MnO‐m‐N‐C nanocomposite involves one‐pot hydrothermal synthesis of Mn₃O₄@polyaniline core/shell nanoparticles from a mixture containing aniline, Mn(NO₃)₂, and KMnO₄, followed by heat treatment to produce N‐doped ultrathin graphitic carbon coated MnO hybrids and partial acid leaching of MnO. The as‐prepared MnO‐m‐N‐C composite catalyst exhibits high electrocatalytic activity and dominant four‐electron oxygen reduction pathway in 0.1 M KOH aqueous solution due to the synergetic effect between MnO and m‐N‐C. The pristine MnO shows little electrocatalytic activity and m‐N‐C alone exhibits a dominant two‐electron process for ORR. The MnO‐m‐N‐C composite catalyst also exhibits superior stability and methanol tolerance to a commercial Pt/C catalyst, making the composite a promising cathode catalyst for alkaline methanol fuel cell applications. The synergetic effect between MnO and N‐doped carbon described provides a new route to design advanced catalysts for energy conversion.     

Fine‐Tuning Intrinsic Strain in Penta‐Twinned Pt–Cu–Mn Nanoframes Boosts Oxygen Reduction Catalysis

Tuning the intrinsic strain of Pt‐based nanomaterials has shown great promise for improving the oxygen reduction reaction (ORR) performance. Herein, reported is a tunable surface strain in penta‐twinned ternary Pt–Cu–Mn nanoframes (NFs). Pt–Cu–Mn ultrafine NFs (UNFs) exhibit ≈1.5% compressive strain compared to Pt–Cu–Mn pentagonal NFs (PNFs) and show the superior activity toward ORR in an alkaline environment. Specifically, the specific and mass activity of Pt–Cu–Mn UNFs are 3.38 mA cm^?2 and 1.45 A mg^?1, respectively, which is 1.45 and 1.71 times higher than that of Pt–Cu–Mn PNFs, demonstrating that compressive strain in NFs structure can effectively enhance the catalytic activity of ORR. Impressively, Pt–Cu–Mn UNFs exhibit 8.67 and 9.67 times enhanced specific and mass activity compared with commercial Pt/C. Theoretical calculations reveal that compression on the surface of Pt–Cu–Mn UNFs can weaken the bonding strengths and adsorption of oxygen‐containing intermediates, resulting in an optimal condition for ORR.     

Strong Electronic Interaction of Amorphous Fe2O3 Nanosheets with Single‐Atom Pt toward Enhanced Carbon Monoxide Oxidation

Platinum‐based catalysts are critical to several chemical processes, but their efficiency is not satisfying enough in some cases, because only the surface active‐site atoms participate in the reaction. Henceforth, catalysts with single‐atom dispersions are highly desirable to maximize their mass efficiency, but fabricating these structures using a controllable method is still challenging. Most previous studies have focused on crystalline materials. However, amorphous materials may have enhanced performance due to their distorted and isotropic nature with numerous defects. Here reported is the facile synthesis of an atomically dispersed catalyst that consists of single Pt atoms and amorphous Fe₂O₃ nanosheets. Rational control can regulate the morphology from single atom clusters to sub‐nanoparticles. Density functional theory calculations show the synergistic effect resulted from the strong binding and stabilization of single Pt atoms with the strong metal‐support interaction between the in situ locally anchored Pt atoms and Fe₂O₃ lead to a weak CO adsorption. Moreover, the distorted amorphous Fe₂O₃ with O vacancies is beneficial for the activation of O₂, which further facilitates CO oxidation on nearby Pt sites or interface sites between Pt and Fe₂O₃, resulting in the extremely high performance for CO oxidation of the atomic catalyst.