Cross‐Linked Polyphosphazene Hollow Nanosphere‐Derived N/P‐Doped Porous Carbon with Single Nonprecious Metal Atoms for the Oxygen Reduction Reaction

Wei, Xuan; Zheng, Diao; Zhao, Ming; Chen, Hongzhong; Fan, Xun; Gao, Bin; Gu, Long; Guo, Yi; Qin, Jianbin; Wei, Jing; Zhao, Yanli; Zhang, Guangcheng

doi:10.1002/anie.202006175

Cited by 141 publications

(79 citation statements)

References 42 publications

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“…[126,246] Similarly, Guo et al presented B-doped Co-N-C active sites (Co-N 3 B) [247] and Zhang and co-workers demonstrated well-dispersed single atom Co-N 2 P 2 sites also showed remarkable ORR electrocatalytic activities (Figure 14i). [35] Such partial substitution of coordination N atoms strategy can also extend to many structures, such as Ni-N 4 , and Zn-N 4 , identified as low ORR activity. For instance, Hou et al reported atomically dispersed Ni-N 3 S sites embedded porous carbon nanosheets and Zhao and co-workers synthesized B, N co-coordinated Zn (ZnB 2 N 2 ) ORR SAC.…”

Section: Adjustment Of Dual-atom Coordinationmentioning

confidence: 99%

Recent Developments of Microenvironment Engineering of Single‐Atom Catalysts for Oxygen Reduction toward Desired Activity and Selectivity

Huang

Tang

et al. 2021

Adv Funct Materials

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Oxygen reduction reaction (ORR) is an essential process for sustainable energy supply and sufficient chemical production in modern society. Singleatom catalysts (SACs) exhibit great potential on maximum atomic efficiency, high ORR activity, and stability, making them attractive candidates for pursuing next-generation catalysts. Despite substantial efforts being made on building diversiform single-atom active sites (SAASs), the performance of the obtained catalysts is still unsatisfactory. Fortunately, microenvironment regulation of SACs provides opportunities to improve activity and selectivity for ORR. In this review, first, ORR mechanism pathways on N-coordinated SAAS, electrochemical evaluation, and characterization of SAAS are displayed. In addition, recent developments in tuning microenvironment of SACs are systematically summarized, especially, strategies for microenvironment modulation are introduced in detail for boosting the intrinsic 4e − /2e − ORR activity and selectivity. Theoretical calculations and cutting-edge characterization techniques are united and discussed for fundamental understanding of the synthesis-construction-performance correlations. Furthermore, the techniques for building SAAS and tuning their microenvironment are comprehensively overviewed to acquire outstanding SACs. Lastly, by proposing perspectives for the remaining challenges of SACs and infant microenvironment engineering, the future directions of ORR SACs and other analogous procedures are pointed out.

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Section: Adjustment Of Dual-atom Coordinationmentioning

confidence: 99%

Recent Developments of Microenvironment Engineering of Single‐Atom Catalysts for Oxygen Reduction toward Desired Activity and Selectivity

Huang

Tang

et al. 2021

Adv Funct Materials

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“…In the literature, advance detectors had been used for HAADF‐STEM images to probe Co SACs on N‐doped carbon. [ 25,29,30 ]…”

Section: Resultsmentioning

confidence: 99%

“…In the literature, advance detectors had been used for HAADF-STEM images to probe Co SACs on N-doped carbon. [25,29,30] Elemental mapping performed with HAADF-STEM image (Figure 1e-j) confirmed a homogenous dispersion of Co single atoms on the GCN sheets, besides O, N, and C atoms. However, as precise identification of the lighter elements with HAADF-STEM is challenging, [31,32] we had to resort to XANES and EXAFS to indirectly determine them (see below).…”

Section: Synthesis and Structural Characterization Of G(cn)co Catalystmentioning

confidence: 99%

Single Co‐Atoms as Electrocatalysts for Efficient Hydrazine Oxidation Reaction

Kadam

Zhang

Zaoralová

et al. 2021

Small

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the extensive use of fossil fuels not only causes severe environmental issues but also compromises efforts to attain a sustainable energy future. [1,2] This has made researchers to investigate cost-effective and non-polluting alternatives to produce energy in a greener manner, through such systems as photovoltaic cells, electrolyzers, and fuel cells. Among them, fuel cells have attracted great attention over the past few years. [1] These devices can convert the chemical energy in fuels such as hydrogen, alcohols, organic acids, and hydrazine into electricity, with high efficiency and minimal greenhouse gas emissions. Among the fuels used in fuel cells, hydrazine is of particular interest for the following three reasons: 1) It produces only N 2 and H 2 O and it does not release the greenhouse gas CO 2 or other harmful byproducts as fossil fuels do; 2) Hydrazine is relatively easy to store and transport with existing infrastructures, as it is liquid at room temperature; and 3) Direct hydrazine fuel cells (DHFCs) have a large theoretical cell voltage (+1.61 V) and higher energy/power density than many other fuel cells (e.g., compared with H 2 /O 2 fuel cell, which is considered one of the best fuel cells). [1] However, Single-atom catalysts (SACs) have aroused great attention due to their high atom efficiency and unprecedented catalytic properties. A remaining challenge is to anchor the single atoms individually on support materials via strong interactions. Herein, single atom Co sites have been developedon functionalized graphene by taking advantage of the strong interaction between Co 2+ ions and the nitrile group of cyanographene. The potential of the material, which is named G(CN)Co, as a SAC is demonstrated using the electrocatalytic hydrazine oxidation reaction (HzOR). The material exhibits excellent catalytic activity for HzOR, driving the reaction with low overpotential and high current density while remaining stable during long reaction times. Thus, this material can be a promising alternative to conventional noble metal-based catalysts that are currently widely used in HzOR-based fuel cells. Density functional theory calculations of the reaction mechanism over the material reveal that the Co(II) sites on G(CN)Co can efficiently interact with hydrazine molecules and promote the NH bond-dissociation steps involved in the HzOR.

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“…As shown in Figure 7d-f, the adsorption free energy of O 2 molecules adsorbed on the Co-N 2 P 2 (−0.27 eV) site was lower than that of the Co-N 4 (−0.13 eV), leading to a faster ORR kinetics of N, P doped PSTA-Co-1000 catalyst. [47] Zhao et al using the DFT calculation further proved Zn-B 2 N 2 SAs with the high selectivity and electrocatalytic activity toward ORR (Figure 7g-i). [18] Considering the different doping type structure can influence on the ORR durability, Chen and co-workers used O and N coordinated atoms to further adjust the d electronic structure of Mn atoms, which exhibited the best catalytic performance for ORR among all studied electrocatalysts.…”

Section: Coordination Atomsmentioning

confidence: 99%

Designed Synthesis and Catalytic Mechanisms of Non‐Precious Metal Single‐Atom Catalysts for Oxygen Reduction Reaction

Tong

Wang

2021

Small Methods

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ORR is proceeded through a two-electron (2e − ) or four-electron (4e − ) pathway. [2][3][4][5] Due to the requirement of high energy conversion efficiency for energy devices, the 4e − pathway directly reducing O 2 to H 2 O is the ideal reaction process. Heretofore, precious metal Pt is still considered as an excellent catalyst for high-efficiency 4e − pathway. [6] However, the high-cost and scarcity limit the extensive use of Pt in practical applications. Thus, development of low-cost and non-precious metal catalysts for energy devices is an intuitively effective strategy.According to the principle that the active sites can be increased by reducing the geometry size, single-atom catalysts (SACs) could expose abundant active sites with maximum atomic utilization and unique physico-chemical properties. [7] It has been presented as a kind of new catalyst members and shows more excellent activity, selectivity, and stability compared with traditional catalysts. Since Thomas et al. first discovered the SACs in 1995, the SACs have been attracting a great deal of attention. [8] In 2000, Heiz et al. prepared SACs containing ≈1-30 Pd atoms for catalyzing acetylene cyclization polymerization reactions. [9] Subsequently, the research of SACs has been rapidly developed into a frontier topic in the field of catalysis since the concept of "single-atom catalysis" was first mentioned by Zhang et al. in 2001. [10] Soon afterwards, Zhang and co-workers proposed an Au-alloyed Pd SACs for ullmann organocatalytic reaction. [11] Subsequently, the Rh SACs loaded on ZnO nanowires could be used to industrially catalyze hydroformylation of olefins by Zhang et al. [12] It showed high activity and selectivity for the hydroformylation of propylene by Zeng et al. [13] Besides, the SACs can be used to catalyze other important electrocatalytic reactions, such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and carbon dioxide reduction reaction (CO 2 RR). For instance, Yu et al. reported that Pt SAC supported on N-doped mesoporous hollow carbon spheres could exhibit excellent HER activity. [14] Wei and co-workers. dispersed Co-P 4 active sites on g-C 3 N 4 as for photocatalytic water splitting reaction. [15] Moreover, Wang et al. used DFT to study a series of transition metals SACs (Fe, Co, Ni, Cu) supported on N-doped graphene, proving that Co-N 4 SAC performed the most excellent OER activity. [16] Wang et al. synthesized Fe SAC on carbonbase with high-efficiency CO 2 RR catalytic activity. [17] Oxygen reduction reaction (ORR) is the important half-reaction for metal-air batteries and fuel cells (FCs), which plays the decisive role for the performance of whole devices. Developing high-efficiency non-precious metal ORR catalysts is urgent and still challenging. Single-atom catalysts (SACs) are considered to be one of the promising substitutes for Pt due to their maximum atom utilization efficiency and mass activity. Despite considerable efforts in preparing various SACs, the reaction mechanism and intrinsic activity modulat...

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Cross‐Linked Polyphosphazene Hollow Nanosphere‐Derived N/P‐Doped Porous Carbon with Single Nonprecious Metal Atoms for the Oxygen Reduction Reaction

Cited by 141 publications

References 42 publications

Recent Developments of Microenvironment Engineering of Single‐Atom Catalysts for Oxygen Reduction toward Desired Activity and Selectivity

Recent Developments of Microenvironment Engineering of Single‐Atom Catalysts for Oxygen Reduction toward Desired Activity and Selectivity

Single Co‐Atoms as Electrocatalysts for Efficient Hydrazine Oxidation Reaction

Designed Synthesis and Catalytic Mechanisms of Non‐Precious Metal Single‐Atom Catalysts for Oxygen Reduction Reaction

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