Outstanding Oxygen Reduction Reaction Activity Research Articles

High surface area micro-mesoporous graphene for electrochemical applications

The manuscript presents results on the influence of external pressure on graphene exfoliation and subsequent 3D structuring by means of liquid-phase exfoliation. In contrast to known and applied exfoliation methods, the current study exploits the enhancement of splitting forces caused by the application of high pressure. The manufacturing pathway allowed to increase the surface area from 750 m2/g (nanoplatelets) to ca. 1100 m2/g (after 3D structuring). Electrochemical studies revealed that the 3D graphene materials were active in the oxygen reduction reaction (ORR). The outstanding ORR activity of 3D structured graphene materials should not be ascribed to heteroatom catalytic centers since such heteroatoms were successively removed upon increasing the carbonization temperature. XPS data showed that the presence of transition metals and nitrogen (usually regarded as catalytic centers) in G-materials was marginal. The results highlight the importance of structural factors of electrodes in the case of graphene-based materials for Zn–air batteries and ORR.

S, N co-doped carbon nanotubes coupled with CoFe nanoparticles as an efficient bifunctional ORR/OER electrocatalyst for rechargeable Zn-air batteries

The development of efficient and cost-effective bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for the commercialization of rechargeable metal-air batteries. Herein, the pyrolysis of a precursor containing g-C3N4, thiourea, cobalt chloride and ferric chloride was used to fabricate S, N co-doped carbon nanotubes functionalized with Co3Fe7 alloy nanoparticles (CoFe/S-N-C). The obtained CoFe/S-N-C catalyst exhibited an ORR half wave potential of 0.855 V (vs. RHE) in 0.1 M KOH, outperforming a commercial Pt/C catalyst (E1/2 = 0.844 V). The catalyst also demonstrated superior OER catalytic activity (1.588 V at 10 mA cm−2) relative to RuO2 in 0.1 M KOH, thus displaying outstanding bifunctional ORR and OER activity. A rechargeable Zn-air battery fabricated using CoFe/S-N-C shows good very performance (maximum power density of 120 mW cm−2 with a specific capacity of 814 mAh g−1) which was superior to a Zn-air battery fabricated using Pt/C and RuO2 as ORR and OER catalysts (92 mW cm−2 and 787 mAh g−1, respectively). Further, the fabricated battery using CoFe/S-N-C showed good stability, offering a discharge voltage ∼ 1.10 V and a recharge voltage ∼ 2.15 V at 10 mA cm−2 over 300 cycles, evidence of the durability of the CoFe/S-N-C catalyst.

Density functional theory study of active sites on nitrogen-doped graphene for oxygen reduction reaction.

Oxygen reduction reaction (ORR) remains challenging due to its complexity and slow kinetics. In particular, Pt-based catalysts which possess outstanding ORR activity are limited in application with high cost and ease of poisoning. In recent years, nitrogen-doped graphene has been widely studied as a potential ORR catalyst for replacing Pt. However, the vague understanding of the reaction mechanism and active sites limits the potential ORR activity of nitrogen-doped graphene materials. Herein, density functional theory is used to study the reaction mechanism and active sites of nitrogen-doped graphene for ORR at the atomic level, focusing on explaining the important role of nitrogen species on ORR. The results reveal that graphitic N (GrN) doping is beneficial to improve the ORR performance of graphene, and dual-GrN-doped graphene can demonstrate the highest catalytic properties with the lowest barriers of ORR. These results provide a theoretical guide for designing catalysts with ideal ORR property, which puts forward a new approach to conceive brilliant catalysts related to energy conversion and environmental catalysis.

Surface microenvironment optimization‐ induced robust oxygen reduction for neutral zinc‐air batteries

AbstractNeutral zinc‐air batteries (ZABs) are promising candidates for the next‐generation power devices with considerably elongated lifetime comparing to conventional alkaline ZABs. However, neutral cathodic oxygen reduction reaction (ORR) is seriously limited by the mass transfer efficiency of hydroxyl due to insufficient interfacial chemical potential‐gradient between catalytic layer and electrolyte. Herein, we highlight that electrochemical oxidation‐induced surface microenvironment optimization could realize optimal chemical potential‐gradient around catalytic sites and bring outstanding neutral ORR activity. The electrodeposited sub‐nano Pt decorated surface‐microenvironment‐optimized Co2N samples (denoted as Pt‐SMO‐Co2N NWs) possessed 92 and 338 mV higher half‐wave potential than commercial Pt/C and pristine Co2N in 0.2 M PBS. As for neutral ZABs, Pt‐SMO‐Co2N NWs cathode delivers a power density of 67.9 mW*cm−2 and displays negligible decay after nearly 80 h stability test at 20 mA*cm−2. In‐depth characterization proposes that remarkable performance improvement originates from optimized microenvironment, which increases the surface chemical potential gradient and facilitates proton coupled electron transfer during ORR. We anticipated that such synergetic optimization of microenvironment and intrinsic activity of active sites is an effective strategy which may be extended to the catalytic reactions beyond ORR.Key points We demonstrated surface microenvironment optimization via in‐situ electrochemical oxidation as an effective way to design highly active ORR catalysts. Surface microenvironment optimization realized significantly enhanced ORR and Zn‐air battery performance in neutral media. Based on ideal material platform, the key role of activating H2O and facilitating proton transfer process in ORR catalysis was revealed.

Understanding the Synergistic Effects of Cobalt Single Atoms and Small Nanoparticles: Enhancing Oxygen Reduction Reaction Catalytic Activity and Stability for Zinc‐Air Batteries

AbstractThe development of earth‐abundant oxygen reduction reaction (ORR) catalysts with high catalytic activity and good stability for practical metal‐air batteries remains an enormous challenge. Herein, a highly efficient and durable ORR catalyst is reported, which consists of atomically dispersed Co single atoms (Co‐SAs) in the form of Co‐N4 moieties and small Co nanoparticles (Co‐SNPs) co‐anchored on nitrogen‐doped porous carbon nanocage (Co‐SAs/SNPs@NC). Benefiting from the synergistic effect of Co‐SAs and Co‐SNPs as well as the enhanced anticorrosion capability of the carbon matrix brought by its improved graphitization degree, the resultant Co‐SAs/SNPs@NC catalyst exhibits outstanding ORR activity and remarkable stability in alkaline media, outperforming Co‐SAs‐based catalyst (Co‐SAs@NC), and benchmark Pt/C catalyst. Density functional theory calculations reveal that the strong interaction between Co‐SNPs and Co‐N4 sites can increase the valence state of the active Co atoms in Co‐SAs/SNPs@NC and moderate the adsorption free energy of ORR intermediates, thus facilitating the reduction of O2. Moreover, the practical zinc‐air battery assembled with Co‐SAs/SNPs@NC catalyst demonstrates a maximum power density of 223.5 mW cm–2, a high specific capacity of 742 W h kg–1 at 50 mA cm–2 and a superior cycling stability.

MIL-101-Derived Mesoporous Carbon Supporting Highly Exposed Fe Single-Atom Sites as Efficient Oxygen Reduction Reaction Catalysts.

Fe single-atom catalysts (Fe SACs) with atomic FeNx active sites are very promising alternatives to platinum-based catalysts for the oxygen reduction reaction (ORR). The pyrolysis of metal-organic frameworks (MOFs) is a common approach for preparing Fe SACs, though most MOF-derived catalysts reported to date are microporous and thus suffer from poor mass transfer and a high proportion of catalytically inaccessible FeNx active sites. Herein, NH2 -MIL-101(Al), a MOF possessing a mesoporous cage architecture, is used as the precursor to prepare a series of N-doped carbon supports (denoted herein as NC-MIL101-T) with a well-defined mesoporous structure at different pyrolysis temperatures. The NC-MIL101-T supports are then impregnated with a Fe(II)-phenanthroline complex, and heated again to yield Fe SAC-MIL101-T catalysts rich in accessible FeNx single atom sites. The best performing Fe SAC-MIL101-1000 catalyst offers outstanding ORR activity in alkaline media, evidenced by an ORR half-wave potential of 0.94V (vs RHE) in 0.1 m KOH, as well as excellent performance in both aqueous primary zinc-air batteries (a near maximum theoretical energy density of 984.2Wh kgZn -1 ) and solid-state zinc-air batteries (a peak power density of 50.6mW cm-2 and a specific capacity of 724.0 mAh kgZn -1 ).

Co3Mo3N—An efficient multifunctional electrocatalyst

Efficient catalysts are required for both oxidative and reductive reactions of hydrogen and oxygen in sustainable energy conversion devices. However, current precious metal-based electrocatalysts do not perform well across the full range of reactions and reported multifunctional catalysts are all complex hybrids. Here, we show that single-phase porous Co3Mo3N prepared via a facile method is an efficient and reliable electrocatalyst for three essential energy conversion reactions; oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER) in alkaline solutions. Co3Mo3N presents outstanding OER, ORR, and HER activity with high durability, comparable with the commercial catalysts RuO2 for OER and Pt/C for ORR and HER. In practical demonstrations, Co3Mo3N gives high specific capacity (850 mA h gZn−1 at 10 mA cm−2) as the cathode in a zinc-air battery, and a low potential (1.63 V at 10 mA cm−2) used in a water-splitting electrolyzer. Availability of Co and Mo d-states appear to result in high ORR and HER performance, while the OER properties result from a cobalt oxide-rich activation surface layer. Our findings will inspire further development of bimetallic nitrides as cost-effective and versatile multifunctional catalysts that will enable scalable usage of electrochemical energy devices.

Atomic‐Level Modulation of Electronic Density at Cobalt Single‐Atom Sites Derived from Metal–Organic Frameworks: Enhanced Oxygen Reduction Performance

AbstractDemonstrated here is the correlation between atomic configuration induced electronic density of single‐atom Co active sites and oxygen reduction reaction (ORR) performance by combining density‐functional theory (DFT) calculations and electrochemical analysis. Guided by DFT calculations, a MOF‐derived Co single‐atom catalyst with the optimal Co1‐N3PS active moiety incorporated in a hollow carbon polyhedron (Co1‐N3PS/HC) was designed and synthesized. Co1‐N3PS/HC exhibits outstanding alkaline ORR activity with a half‐wave potential of 0.920 V and superior ORR kinetics with record‐level kinetic current density and an ultralow Tafel slope of 31 mV dec−1, exceeding that of Pt/C and almost all non‐precious ORR electrocatalysts. In acidic media the ORR kinetics of Co1‐N3PS/HC still surpasses that of Pt/C. This work offers atomic‐level insight into the relationship between electronic density of the active site and catalytic properties, promoting rational design of efficient catalysts.

Atomic-Level Modulation of Electronic Density at Cobalt Single-Atom Sites Derived from Metal-Organic Frameworks: Enhanced Oxygen Reduction Performance.

Demonstrated here is the correlation between atomic configuration induced electronic density of single-atom Co active sites and oxygen reduction reaction (ORR) performance by combining density-functional theory (DFT) calculations and electrochemical analysis. Guided by DFT calculations, a MOF-derived Co single-atom catalyst with the optimal Co1 -N3 PS active moiety incorporated in a hollow carbon polyhedron (Co1 -N3 PS/HC) was designed and synthesized. Co1 -N3 PS/HC exhibits outstanding alkaline ORR activity with a half-wave potential of 0.920 V and superior ORR kinetics with record-level kinetic current density and an ultralow Tafel slope of 31 mV dec-1 , exceeding that of Pt/C and almost all non-precious ORR electrocatalysts. In acidic media the ORR kinetics of Co1 -N3 PS/HC still surpasses that of Pt/C. This work offers atomic-level insight into the relationship between electronic density of the active site and catalytic properties, promoting rational design of efficient catalysts.

Eu2O3–Cu/NC nanocomposite catalyst with improved oxygen reduction reaction activity for Zn-air batteries

Rare earth oxide promoted transition metal composite catalyst Eu2O3–Cu/NC with outstanding oxygen reduction reaction (ORR) performance, is constructed by hydrothermal and subsequent high-temperature calcination, considering replacing Pt/C. This synthesis method yields Eu2O3–Cu nanoparticles with uniform distribution, improved oxygen vacancies and increased content of N-doping. And the strong synergistic effect was created between promoter Eu2O3 and chief Cu. In addition, the accommodate adsorption and transfer of O species endow Eu2O3–Cu/NC the improved ORR activity than Eu2O3/NC and Cu/NC. Meanwhile, the stability of Eu2O3–Cu/NC is also strengthened compared to Cu/NC on account of the interaction of active sites, and the H2O2 yield of Eu2O3–Cu/NC is very low. For practical application, a rechargeable Zn-air battery with an air cathode of Eu2O3–Cu/NC displays a larger power density, excellent charge-discharge cycle stability and good rate capability. The designed composite shows potential application prospects in the fields of energy conversion.

The role of S in the Co-N-S-C catalysis system towards the ORR for proton exchange membrane fuel cells

Density functional theory (DFT) was used to calculate the thermodynamic free energy changes of the possible basic reaction steps of the oxygen reduction reaction (ORR) on both sides of the active center of the S-doped CoN4-G catalyst. It is found that the adsorption energies on CoN4 active site of these catalysts increase in the range: O < OH < Co-ad OH < OOH < O2 < H2O2 < H2O on these catalysts and the trend of adsorption energy change for all O-contained intermediates is almost consistent. The large thermodynamic driving forces for the OOH reduction to O* (or to 2OH*) and the small thermodynamic driving forces for the H2O2 generation indicate that the four electron pathway is more is more advantageous to proceed than the 2e− pathway. Moreover, the last reduction step (OH* + H+ + e− → H2O + *) with the largest ΔG value for all catalysts is the rate-determining step (RDS) in thermodynamic. In the most cases of S-doped catalysts, it is helpful to increase the activity of CoN4 active center. Moreover, the active center on the dented side has a higher ORR activity than its corresponding raised side for the case that S is adjacent to the CoN4 active center. Dented side of CoN4S1-G exhibits the largest on-set potentials of 0.65 V which is larger than the on-set potential of un-doped S CoN4-G catalyst (0.40 V). The d-band center of Co is much farther from the Fermi level or a larger HOMO-LUMO gap imply that the catalyst is not beneficial to the adsorption of the O-contained species, thus showing a larger on-set potential and more outstanding ORR activity.

Silk gel-based N self-doped porous activated carbon as an efficient electrocatalyst in neutral, alkaline and acidic medium

The nitrogen (N) self-doped porous activated carbons (SGC-T) are synthesized from silk gel at different carbonization temperature. Among of SGC-T, as-prepared SGC-900 exhibits outstanding oxygen reduction reaction (ORR) electrocatalytic activities in neutral, alkaline and acidic medium attributed to the synergistic effect of graphitization and active sites. And the high specific surface area (476.42 m2 g−1), pore volume (1.06 cm3 g−1), pore diameter (12.72 nm), degree of graphitization (90.16 at. % of C) and content of ORR active N (1.80 at. % of N-ORR: including pyridinic-N and graphitic-N) for SGC-900 provides suitable graphite structure to electron transfer and exposes many more active sites to participate in the process of ORR. Reasonably, SGC-900 displays superior ORR activity, stability and anti-poisoning in 50 mM PBS, 0.1 M KOH solution and 0.5 M H2SO4 solution through more efficient electron pathway. Furthermore, SGC-900 indicates excellent ORR performance in the practical application of microbial fuel cell (MFC) with high output voltage (498.66 ± 10.19 mV) and maximum power density (507.13 ± 7.06 mW m−2). These results suggest, as one activated carbon (AC), SGC-900 possesses broad application prospects in the field of fuel cells.

An efficient ruthenium-based dual-electrocatalyst towards hydrogen evolution and oxygen reduction reactions

The development of highly efficient and durable catalysts for production and storage of clean energy remains a formidable challenge. Herein, a bifunctional electrocatalyst composed of ultrasmall ruthenium nanoparticles confined within a hollow nitrogen-doped carbon spheres (Ru/HNCS) was designed and synthesized through the pyrolysis of Ru3+ coordinated polydopamine layers. The as-synthesized Ru/HNCS with Ru content even below 0.1 wt% exhibited excellent catalytic activities towards both hydrogen production and oxygen reduction. When catalyzing hydrogen evolution reaction, a low overpotential of 39 mV was sufficiently to achieve the current density of 10 mA cm−2 in acidic media and the corresponding Tafel slope was only 30 mV dec−1. Furthermore, Ru/HNCS also exhibited outstanding oxygen reduction reaction activity with a half-potential of 0.72 V and an onset potential of 0.83 V, as well as high stability and palmary anti-poisoning capability for methanol in basic electrolyte. This Ru/HNCS might be a promising alternative to Pt-based electrocatalysts in energy conversion and storage.

Coexisting Single-Atomic Fe and Ni Sites on Hierarchically Ordered Porous Carbon as a Highly Efficient ORR Electrocatalyst.

The development of oxygen reduction reaction (ORR) electrocatalysts based on earth-abundant nonprecious materials is critically important for sustainable large-scale applications of fuel cells and metal-air batteries. Herein, a hetero-single-atom (h-SA) ORR electrocatalyst is presented, which has atomically dispersed Fe and Ni coanchored to a microsized nitrogen-doped graphitic carbon support with unique trimodal-porous structure configured by highly ordered macropores interconnected through mesopores. Extended X-ray absorption fine structure spectra confirm that Fe- and Ni-SAs are affixed to the carbon support via FeN4 and NiN4 coordination bonds. The resultant Fe/Ni h-SA electrocatalyst exhibits an outstanding ORR activity, outperforming SA electrocatalysts with only Fe- or Ni-SAs, and the benchmark Pt/C. The obtained experimental results indicate that the achieved outstanding ORR performance results from the synergetic enhancement induced by the coexisting FeN4 and NiN4 sites, and the superior mass-transfer capability promoted by the trimodal-porous-structured carbon support.

A novel cobalt and nitrogen co-doped mesoporous hollow carbon hemisphere as high-efficient electrocatalysts for oxygen reduction reaction

Exploring a cheap catalyst with effective activity for oxygen reduction reaction (ORR) to replace precious metal electrocatalysts has gained tremendous attention for several decades. In this study, we designed and synthesized cobalt and nitrogen supported on mesoporous hollow carbon hemisphere (Co/N/HCHs) nanocomposites by a facile and economical approach. Semisphere-shaped mesoporous hollow carbon is self-generated using silica particles as template, followed by a pyrolysis-etching process; and exhibits high electrical conductivity and high specific surface. The unique porous structure of carbon provides significant number of the abundant defective sites and shortens the mass transfer pathway, leading to a greatly enhanced electrocatalytic activity with mainly 4e- reduction. Moreover, the synergistic effects of large electrochemically active areas and good electrical conductivity, resulting from the introduction of Co and N heteroatom, are the main reason for displaying outstanding ORR activity with a high half-wave potential of 0.8 V and the electron transfer numbers of 3.89. Furthermore, an excellent long-term stability (the current density retention of 87.0%) and superb methanol tolerance in alkaline medium are achieved. Undoubtedly, this demonstrates a potential way to strategically design the non-precious metal doped carbon catalysts for wider practical applications.

Size-Controlled Synthesis of L10-CoPt Intermetallic Fuel Cell Catalysts on Nitrogen-Doped Mesoporous Graphitized Carbon Support

Ordered intermetallic nanoparticles are promising electrocatalysts with enhanced activity and durability for the oxygen-reduction reaction (ORR) in proton-exchange membrane fuel cells (PEMFCs). However, after subjecting to a widely used postsynthesis annealing treatment, the particle size of intermetallic catalysts inevitably increases, leading to a poor performance in practical fuel cell application. In this work, ordered L10-CoPt intermetallic catalyst of small particle size was prepared through using nitrogen-doped mesoporous graphitized carbon (NMGC) support. The porous feature and nitrogen doping of NMGC support immobilized CoPt particles and prevented sintering during annealing treatment. These small and ordered L10-CoPt nanoparticles exhibit outstanding ORR activity (~ 1.18 A/mgPt) and superior high current density in fuel cell testing. Moreover, this L10-CoPt/NMGC catalyst performs remarkably enhanced stability in comparison with L10-CoPt/high surface area carbon (HSC) counterpart and commercial Pt/C catalyst, surpassing the DOE 2020 target. The enhancement in catalyst durability can be attributed to strong particles-support interaction via nitrogen heteroatoms and the strengthened p bonding. To better understand the support effect on particle growth, L10-CoPt particles on NMGC with different porosity/graphitization were prepared and their fuel cell performances were systematically studied. This study demonstrates an effective strategy to control the particle size of intermetallic catalysts with using NMGC support, which achieves excellent practical fuel cell performance.

Metal‐organic framework‐derived Fe/Cu‐substituted Co nanoparticles embedded in CNTs‐grafted carbon polyhedron for Zn‐air batteries

AbstractMetal‐organic frameworks (MOFs) and MOF‐derived materials have attracted great attention as alternatives to noble‐metal based electrocatalysts owing to their intriguing structure properties, especially for high efficiency and stable oxygen reduction reaction (ORR). Herein, we employed a one‐pot reaction to make a multimetal (Fe, Co, Cu, and Zn) mixed zeolitic imidazolate framework (MM‐ZIF) via adopting a simple in situ redox reaction. Further pyrolysis of the target MM‐ZIF, a highly porous carbon polyhedron (FC‐C@NC) grafted with abundant carbon nanotubes was obtained, in which ultrasmall Co nanoparticles with partial lattice sites substituted by Fe and Cu were embedded. The obtained FC‐C@NC possessed large surface area, highly porous structure, widely‐spread metal active sites, and conductive carbon frameworks, contributing to outstanding ORR activity and long‐term stability. It displayed superior tolerance to methanol crossover and exceeded the commercial Pt/C catalyst and most previously reported non‐noble‐metal catalysts. Impressively, the as‐produced FC‐C@NC‐based zinc‐air battery afforded an open‐circuit potential of 1.466 V, a large specific capacity of 659.5 mAh/g, and a high gravimetric energy density of 784.3 Wh/kgZn, significantly outperforming the Pt/C‐based cathode.

Atomically dispersed hierarchically ordered porous Fe–N–C electrocatalyst for high performance electrocatalytic oxygen reduction in Zn-Air battery

Rational design and synthesis of non-precious metal electrocatalysts for highly efficient oxygen reduction reaction (ORR) is urgently required. Recently, single atom catalysts (SACs) have sparked intense interests due to their maximum atom utilization efficiency and excellent properties in electrocatalysis. Herein, we reported an efficient ORR electrocatalyst with atomically dispersed FeN4 sites anchored on 3D hierarchically ordered microporous-mesoporous-macroporous nitrogen doped carbon (3DOM Fe–N–C). Owing to the synergism of highly dispersed FeN4 active sites and 3D hierarchically ordered porous architecture, 3DOM Fe–N–C-900, which was obtained via pyrolysis of ferrocene-encapsulated macro-microporous ZIF-8 precursor at 900 °C, exhibited an outstanding ORR activity in both alkaline (E1/2 of 0.875 V) and acid mediums (E1/2 of 0.784 V), as well as superior stability (only changed 2 mV after 10,000 cycles in alkaline medium). Moreover, 3DOM Fe–N–C-900 as ORR catalyst in zinc-air battery achieved a high power density of 235 mW cm−2 and a high specific capacity of 768.3 mAh g−1, exceeding that driven by Pt/C. Our results revealed that the 3D hierarchically porous architecture of electrocatalysts could facilitate mass transport and increase the accessibility of active sites, thus optimizing their performances in ORR. This work well demonstrated the importance of rationally engineering porous structure of the catalyst for highly efficient ORR.

Improving the Catalytic Performance of Co/N/C Catalyst for Oxygen Reduction Reaction by Alloying with Fe

Transition metal and nitrogen co-doped carbon-based nanomaterial has been used as non-precious metal catalyst for oxygen reduction reaction (ORR). In this work, bamboo-like carbon nanotubes structured FeCo/N/C electrocatalyst is proved to show much enhanced performance compared with Co/N/C. MIL-53 (Fe) is used as iron source, MIL-53 (Co) is used as cobalt source and ZIF-8 as carbon source. The ball-milling procedure plays a significant role for the distribution of Fe and Co component and the formation of carbon nanotubes, which is believed to enhance the catalytic performance due to abundant electrocatalytic active sites and efficient mass transfer. The as prepared sample obtained by optimized preparation conditions exhibits outstanding ORR activity in acid solution with an onset potential of 0.96 V vs RHE (reversible hydrogen electrode), half-wave potential of 0.78 V, and a current density of 0.575 m A cm−2 at 0.7 V in a H2-O2 fuel cell test, which provides an ideal viewpoint to develop highly efficient catalyst for the oxygen reduction reaction. The high ORR performance could be attributed to the synergistic effect between Fe and Co and the high conductivity and mass transfer of the carbon nanotube.

In‐Situ Electrodeposition of Rhodium nanoparticles Anchored on Reduced Graphene Oxide nanosheets as an Efficient Oxygen Reduction Electrocatalyst

A simple, versatile, and cost‐effective one‐pot electrochemical deposition is used to fabricate rhodium (Rh) nanoparticles decorated surface of reduced graphene oxide (rGO) functionalized glassy carbon electrode (GCE) for oxygen reduction reaction (ORR) in alkaline media. The chemical and physical structure of the sample is probed via transmission electron microscopy, rotating disk electrode (RDE), X‐ray photoelectron spectroscopy, linear sweep voltammetry, and Raman spectroscopy. The synergistic effects between the unique properties of Rh nanoparticles and rGO creates such innovative hybrid that exhibits a catalytic activity comparable to that of the commercial platinum electrocatalyst (Pt/C). As a result, the as‐electrodeposited Rh@rGO hybrid exhibits outstanding ORR activity in alkaline media, as evidenced by a larger diffusion‐limited current, greater positive onset potential, much better stability and methanol tolerance than Pt/C under the same conditions.