Carbon-based electrocatalysts for sustainable energy applications

Synthesis and characterization of high performing Fe-N-C catalyst for oxygen reduction reaction (ORR) in Alkaline Exchange Membrane Fuel Cells

Earth-abundant transition metal and metal oxide nanomaterials: Synthesis and electrochemical applications

Graphene and g-C 3 N 4 based photocatalysts for NO x removal: A review

The electrocatalytic nitrogen reduction reaction (NRR) has much prospect for substituting the energy-consuming Haber–Bosch process. Nevertheless, its sluggish reaction kinetics and the competing hydrogen evolution reaction always result in limited ammonia yield and low faradaic efficiency (FE). In this work, an Fe-decorated porphyrinic metal–organic framework (MOF) is employed as a precursor to construct single-atom Fe implanted nitrogen-doped carbon catalysts (Fe1-N-C) through a mixed ligand strategy. Benefiting from the highly dispersed single-atom Fe sites, hierarchically porous structure and good conductivity, Fe1-N-C shows a FE of 4.51% and an ammonia yield rate of 1.56 × 10−11 mol cm−2 s−1 at −0.05 V versus the reversible hydrogen electrode, superior to those of Co1-N-C and Ni1-N-C. Theoretical calculations reveal that Fe1-N-C shows the lowest energy barrier of the rate-determining step during the NRR process, consistent with its highest activity obtained in experiments. This work reveals the unique potential of single-atom catalysts for the electrochemical NRR and provides in-depth insights into the catalytic mechanism of the NRR.

Single-atom catalysts templated by metal–organic frameworks for electrochemical nitrogen reduction

Creating active and stable electrocatalysts remains a highly desirable and critical goal in the fields of catalysis and clean energy conversion. Single-atom catalyst (SAC), as a new research frontier in heterogeneous catalysis, has demonstrated emerging prospects for many electrocatalytic reactions. Support-assisted pyrolysis approaches are widely used in the synthesis of single-atom electrocatalysts. While extensive efforts have been devoted to increase the loading of the atomically dispersed metal sites, the role of the support in creating these active metal sites remains largely unexplored. Herein, we compare catalysts created by support-free and support-assisted pyrolysis of vitamin B12 and cobalt tetramethoxyphenylporphyrin, respectively, and demonstrate an important effect of support-induced structural reconstruction that directly controls the activation of SAC. Electrochemical studies show support-free catalysts are inactive for oxygen reduction reaction whereas the support-assisted pyrolysis yield...

Tuning the Performance of Single-Atom Electrocatalysts: Support-Induced Structural Reconstruction

A series of Cu–Mn mixed oxides were prepared via a facile co-precipitation method and used as catalysts for diesel soot combustion in NOx/O2/N2. It is found that the chemical composition in the Cu–Mn mixed oxides has a significant influence on both morphology and catalytic activity. When the Cu/Mn atomic ratio was optimized to be 1, a distinctive pure spinel phase of Cu1.5Mn1.5O4 was obtained (named Cu1Mn1), which exhibited superior catalytic activity (e.g., finishing combustion temperature (Tf) = 360 °C, in loose contact mode). The excellent catalytic activity of Cu1Mn1 was mainly attributed to the following aspects: (1) distinct morphological features: the well-dispersed Cu1Mn1 microspheres with a rough surface could contact soot particles sufficiently, and the stacked pores between the loosely packed nanoparticles within the microspheres could facilitate the diffusion of gaseous O2, NO and NO2; and (2) the high intrinsic activity of the Cu1.5Mn1.5O4 phase: the abundant adsorbed oxygen species (Oads) is beneficial to the direct oxidation of soot into CO2, and the enormous Cu+–Mnλ+ (λ = 3, 4, hereinafter inclusive) cation pairs could facilitate the production of the strong oxidant NO2, and the interaction between Cu2+ and NO2 would lead to high enhancement efficiency of NO2 for soot combustion. This facile strategy for the high activity spinel phase towards catalytic soot combustion shows great promise for practical applications.

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Facile synthesis of spinel Cu1.5Mn1.5O4 microspheres with high activity for the catalytic combustion of diesel soot

A nitrogen-doped vesicle-like porous carbon with well-integrated dual iron-based catalytic sites was developed through direct pyrolysis of inexpensive and abundant precursors. Benefiting from the mesoporous structures with synchronous construction of Fe-Nx and Fe/Fe3 C@NC sites, the optimized catalyst exhibited outstanding performance for the oxygen reduction reaction (ORR) in alkaline media, even superior to the commercial Pt/C catalyst. Detailed characterizations revealed that Fe/Fe3 C@NC sites can make major catalytic contributions in basic media, whereas the Fe-Nx sites were found to play an indispensable role for ORR in acidic media.

Nitrogen‐Doped Carbon Vesicles with Dual Iron‐Based Sites for Efficient Oxygen Reduction

An enhanced catalytic activity and improved reusability were achieved by applying facile KNO3 modification during the synthesis of a copper‐manganese mixed oxide (CuMnO). Upon KNO3 modification, the characteristic finishing temperature (Tf) of catalytic soot combustion was decreased from 360 °C for CuMnO to 338 °C for the K‐modified product CuMnO(K). Moreover, this Tf value for CuMnO(K) remained remarkably low (346 °C) even after five runs of an activity test. The excellent performance of CuMnO(K) is attributed to its well‐dispersed nanoparticle morphology, which is totally different from the microspherical features of CuMnO and is beneficial for its sufficient contact with the soot particles. Additionally, an interesting phase evolution of CuMnO(K) was observed for the first time from Cu1.5Mn1.5O4 to the mixed phases of CuO, K2Mn4O8, and MnOx during the consecutive test runs. These mixed phases are believed to be responsible for the enhancement and stabilization of the catalytic activity. Furthermore, the mechanism for the morphology transformation upon KNO3 modification and for the phase evolution during soot combustion was investigated.

Effect of Potassium Nitrate Modification on the Performance of Copper‐Manganese Oxide Catalyst for Enhanced Soot Combustion

A series of CuBi co-doped mesoporous zeolite Beta (CuxBiy-mBeta) were prepared by a facile one-pot hydrothermal treatment approach and were characterized by XRD, N2 adsorption-desorption, TEM/SEM, XPS, H2-TPR, NH3-TPD and in situ DRIFTS. The catalysts CuxBiy-mBeta were applied to the removal of NOx by selective catalytic reduction with ammonia (NH3-SCR), especially the optimized Cu1Bi1-mBeta achieved the high efficiency for the removal of NOx and N2 selectivity, superior water and sulfur resistance as well as good durability. The excellent catalytic performance could be attributed to the acid sites of the support and the synergistic effect between copper and bismuth species. Moreover, in situ DRIFTS results showed that amides NH2 and NH4+ generated from NH3 adsorption could be responsible for the high selective catalytic reduction of NOx to N2. In addition, a possible catalytic reaction mechanism on Cu1Bi1-mBeta for the removal of NOx by NH3-SCR was proposed for explaining this catalytic process.

Pan Linyu

Papers

Tuning the Performance of Single-Atom Electrocatalysts: Support-Induced Structural Reconstruction

Facile synthesis of spinel Cu1.5Mn1.5O4 microspheres with high activity for the catalytic combustion of diesel soot

Nitrogen‐Doped Carbon Vesicles with Dual Iron‐Based Sites for Efficient Oxygen Reduction

Effect of Potassium Nitrate Modification on the Performance of Copper‐Manganese Oxide Catalyst for Enhanced Soot Combustion

One-pot hydrothermal synthesis of CuBi co-doped mesoporous zeolite Beta for the removal of NOx by selective catalytic reduction with ammonia.