Chinese Journal of Catalysis
2023, Vol. 45
Online: 18 February 2023

Cover: Prof. Chuanxin He and coworkers in their article on pages 95–106 reported the facile synthesis of ultrasmall bismuth nanoparticles encapsulated in carbon nanofibers by electrospinning and pyrolysis for electrochemical CO2 reduction reaction. The prepared electrocatalyst possessed overwhelming superiorities in the mass activity and formate yield rate.
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Metal-organic frameworks for catalysis: Fundamentals and future prospects
Long Jiao, Hai-Long Jiang
2023, 45:  1-5.  DOI: 10.1016/S1872-2067(22)64193-7
Abstract ( 37 )   HTML ( 7 )   PDF (1535KB) ( 60 )  

The past three decades have witnessed significant development of metal-organic frameworks (MOFs) for heterogeneous catalysis. At the crossroads of development, the fundamentals on the design of MOF-based catalysts along with the specific uniqueness of MOFs for catalysis are summarized in this Comment. Moreover, the bottlenecks limiting the further development and opportunities moving this field forwards are further discussed.

Chemical functionalized noble metal nanocrystals for electrocatalysis
Qi Xue, Zhe Wang, Yu Ding, Fumin Li, Yu Chen
2023, 45:  6-16.  DOI: 10.1016/S1872-2067(22)64186-X
Abstract ( 11 )   HTML ( 3 )   PDF (7178KB) ( 28 )  

Electrocatalysis is an interface-dominated process, in which the activity of the catalyst highly relates to the adsorption/desorption behaviors of the reactants/intermediates/products on the active sites. From the perspective of catalyst design, the chemical functionalization design on noble metal surfaces will inevitably affect the reaction process, which is considered to be one of the effective strategies to tune the electrocatalytic performance of noble metal nanocrystals. Polyamines (PAM) with high stability and good coordination ability have been widely studied as important functional molecules. In this account, we first introduce the PAM-assisted synthesis mechanism of noble metal nanocrystals, which provides a theoretical basis and guidance for their design and optimization with controllable morphology. Then, the effects of adsorbed PAM on the electronic structure, geometric structure, electrode/electrolyte interface structure and catalytic reaction pathway of noble metal-based catalysts are specifically described. The internal mechanism of noble metal-PAM interfacial effect increasing catalyst activity and selectivity is stated, and the latest research progress of PAM functionalized catalysts applied in important reactions is listed, such as hydrogen evolution reaction, oxygen reduction reaction, formic acid oxidation reaction, and nitrate reduction reaction, and so on. These findings open a new avenue for constructing advanced electrocatalysts based on inorganic/organic polymer-mediated interface engineering in various energy-related catalysis/electrocatalysis fields. Finally, the current challenges and future prospects of PAM molecule functionalized noble metal electrocatalysts are proposed.

Design principle and synthetic approach of intermetallic Pt-M alloy oxygen reduction catalysts for fuel cells
Xuan Liu, Jiashun Liang, Qing Li
2023, 45:  17-26.  DOI: 10.1016/S1872-2067(22)64165-2
Abstract ( 44 )   HTML ( 3 )   PDF (3668KB) ( 43 )  

Developing high-performance Pt-M (M = transition metal) intermetallic alloy catalysts for oxygen reduction reaction (ORR) are key to achieving large-scale applications of proton exchange membrane fuel cells (PEMFCs). It is urgent to clarify the general rules to design and prepare intermetallic Pt-M catalysts with high ORR activity and stability. In this account, the basic principles for disorder-order phase transition in terms of thermodynamics and kinetics are first introduced and our recent efforts in synthesizing fully-ordered Pt-M intermetallic nanocrystals (iNCs) with well-defined L10-ordering structures are described. Then the effective strategies for further enhancing the activity and stability of L10-Pt-M ORR catalysts for PEMFCs are exemplified. We hope that this account will provide some significant insights into the research and development of intermetallic Pt-M alloy ORR catalysts for the applications of PEMFCs and other electrochemical energy conversion technologies in the future.

Defect engineering of electrocatalysts for metal-based battery
Xiaoni Liu, Xiaobin Liu, Caixia Li, Bo Yang, Lei Wang
2023, 45:  27-87.  DOI: 10.1016/S1872-2067(22)64168-8
Abstract ( 38 )   HTML ( 3 )   PDF (52452KB) ( 32 )  

To conquer the instability of clean energy, developing high performance energy storage devices is of vital importance. Among them, metal‐based battery (such as Metal-air batteries and metal-sulfur batteries) exhibited high potential for application due to their low lost and high energy density. The rational design of electrode materials (catalysts) plays an important role in improving the energy storage efficacy for metal based batteries and promoting the development of renewable energy technology. With the continuous development of energy storage technology and the in-depth exploration of the electrode reaction mechanism, the researchers found that the electrochemical performances of batteries can be significantly improved by modifying the electrode materials through defect engineering. The introduction of defects in the catalytic electrode material can not only adjust the electronic structure of the catalyst and enhance intrinsic activity, but also the defects can provide a large number of unsaturated sites and provide more favorable active centers for improving the electrochemical kinetics. This paper systematically reviews the action mechanism of defect engineering in the electrocatalytic process and the latest progress in energy storage developments. The reaction mechanism of metal‐air batteries and metal‐sulfur batteries is introduced firstly. Afterward, the types of defects (intrinsic defects, anion vacancy, cation vacancy, lattice distortion, and heteroatomic doping) and their preparation strategies are summarized. Subsequently, with the typical metal‐based batteries (Zn-air battery, Li-O2 battery, Li-CO2 battery, Li-S battery, Na-S battery, etc.) as the foothold, the important role of defect engineering in its application is summarized in detail. Finally, the current challenges and development prospects of metal-based batteries are proposed, aiming to broaden the catalytic electrode materials through defect engineering and promote the commercialization process of clean energy storage devices.

Promoting hydrogen evolution reaction with a sulfonic proton relay
Ni Wang, Xue-Peng Zhang, Jinxiu Han, Haitao Lei, Qingxin Zhang, Hang Zhang, Wei Zhang, Ulf-Peter Apfel, Rui Cao
2023, 45:  88-94.  DOI: 10.1016/S1872-2067(22)64183-4
Abstract ( 5 )   HTML ( 2 )   PDF (1442KB) ( 26 )  
Supporting Information

Enzymes can activate otherwise unreactive substrates by using residues precisely located in the active sites. We herein report on a Ga porphyrin which bears a second-sphere sulfonic group (named as 1) and its high efficiency for the electrocatalytic hydrogen evolution reaction (HER). Complex 1 can achieve a large TOF value of 1.3 × 105 s−1 at low 295-mV overpotential with weak acetic acid (HOAc) as the proton source. Notably, 1 can catalyze H2 generation at potentials close to the thermodynamic HER equilibrium, but the sulfonic-free analogues require >250 mV more cathodic potentials to initiate HER. Mechanistic studies showed that two-electron reduced Ga porphyrins were protonated to form GaIII-H. For 1, its GaIII-H underwent rapid protonolysis with HOAc to evolve H2, but for sulfonic-free analogues, their GaIII-H required further reduction at more cathodic potentials to trigger catalysis. This work presents a synthetic molecular catalyst to achieve high HER rates under low overpotentials by promoting the protonolysis of metal hydrides with otherwise unreactive weak acids.

Boosting electrocatalytic CO2 reduction to formate via carbon nanofiber encapsulated bismuth nanoparticles with ultrahigh mass activity
Yan Kong, Xingxing Jiang, Xuan Li, Jianju Sun, Qi Hu, Xiaoyan Chai, Hengpan Yang, Chuanxin He
2023, 45:  95-106.  DOI: 10.1016/S1872-2067(22)64177-9
Abstract ( 10 )   HTML ( 4 )   PDF (9207KB) ( 28 )  
Supporting Information

Electrochemical CO2 conversion is one of the most promising technologies to achieve carbon neutrality. However, it still suffers from some nonnegligible challenges on low production rate and unsatisfied current densities for potential large-scale applications. Herein, we prepare ultrasmall Bi nanoparticles uniformly encapsulated in the carbon nanofibers through electrospinning techniques, which is denoted as Bi/CNFs-900. Gratifyingly, this Bi/CNFs-900 catalyst demonstrates excellent performance and stability on CO2 electro-reduction in a broad potential window. Specifically, it can produce formate with a Faradaic efficiency over 90% and a high partial current density of -235.3 mA cm-2 at −1.23 V vs. RHE in a flow-cell. Furthermore, the confinement effect of carbon nanofibers largely restricts the severe aggregation of bismuth nanoparticles during synthesis as well as electrolysis procedure, which greatly increases the accessible active sites and decreases the actual mass fraction of bismuth composition. Consequently, Bi/CNFs-900 not only achieves ultrahigh mass activity of -1.6 A mgBi-1, but also possesses an unprecedented formate production rate of 4403.3 μmol h-1 cm-2. DFT calculations and in situ Raman spectroscopy further uncover the possible reaction mechanism for CO2 reduction toward formate. These results could provide an economical and industrial-viable strategy for the preparation of electrocatalysts in CO2 reduction.

Facile fabrication of atomically dispersed Ru-P-Ru ensembles for efficient hydrogenations beyond isolated single atoms
Chao Nie, Xiangdong Long, Qi Liu, Jia Wang, Fei Zhan, Zelun Zhao, Jiong Li, Yongjie Xi, Fuwei Li
2023, 45:  107-119.  DOI: 10.1016/S1872-2067(22)64172-X
Abstract ( 7 )   HTML ( 1 )   PDF (3577KB) ( 27 )  
Supporting Information

It is of great significance for upgrading single-atom catalysts (SACs) to further improve their intrinsic catalytic activities while maintaining the merits of maximum atom utilization and high selectivity. Here, we report a simple and practical strategy to construct phosphorus (P) atom bridged ruthenium (Ru) ensemble (Ru-P-Ru) in carbon skeleton, which is achieved by redispersing Ru clusters with C-P species and in-situ generated PH3. The turnover frequency of the Ru-P-Ru catalyst is 9-fold higher than that of the RuP4 SAC in the selective hydrodeoxygenation of o-phthalic anhydride, as well as other diverse hydrogenations of C=X bonds (X = O, C, N) with good recyclability. Experimental and computational studies reveal that the d-band centers of Ru in the Ru-P-Ru are closer to the Fermi level than that of isolated Ru SAC, significantly promoting the absorption and activation of substrates. This fabrication strategy is also applicable to other M-P-M catalysts, enriching the knowledge of atomically dispersed catalysts.

Controlling the reactions of free radicals with metal-radical interaction
Zhipeng Huang, Yang Yang, Junju Mu, Genheng Li, Jianyu Han, Puning Ren, Jian Zhang, Nengchao Luo, Ke-Li Han, Feng Wang
2023, 45:  120-131.  DOI: 10.1016/S1872-2067(22)64181-0
Abstract ( 8 )   HTML ( 2 )   PDF (1028KB) ( 25 )  
Supporting Information

Radicals are key intermediates in numerous reactions. Their high reactivity enables various transformations to occur under mild conditions, however, also brings great challenges to control their reactions especially over heterogeneous catalysts. Here we propose to use metal nanoparticles to directly steer the conversion of free radical species. Results from photocatalytic reactions, in situ transient absorption spectroscopy, and theoretical simulation demonstrate that supported Pd nanoparticles can efficiently stabilize free radical species generated from photo-excited TiO2, and thus manipulate their conversion on catalyst surface, owing to the enhanced electronic interactions between metal and radical species. These understandings are crucial for the design of advanced heterogeneous catalytic systems with controllable radical reactions.

Enhanced photocatalytic H2O2 production over Pt(II) deposited boron containing metal-organic framework via suppressing the simultaneous decomposition
Yujie Li, Yuanyuan Liu, Zeyan Wang, Peng Wang, Zhaoke Zheng, Hefeng Cheng, Ying Dai, Baibiao Huang
2023, 45:  132-140.  DOI: 10.1016/S1872-2067(22)64163-9
Abstract ( 18 )   HTML ( 1 )   PDF (1736KB) ( 30 )  
Supporting Information

Photocatalytic H2O2 evolution has received extensive attention as an environmentally friendly method, which is a dynamic process of formation and decomposition. At present, researches mainly focus on the H2O2 formation, while the decomposition of H2O2 is rarely studied. In addition, platinum as a cocatalyst plays an important role in enhancing the photocatalytic activity, but the effects of platinum valence state on the activity, especially towards H2O2 formation and decomposition, has not been studied in detail to the best of our knowledge. In this work, platinum with different valence state were deposited onto boron containing metal organic frameworks (UiO-67-B), and the roles of Pt(0), Pt(II) and Pt(IV) in the photocatalytic H2O2 process were explored in detail. Both the experimental results and theoretical calculations indicate that the presence of Pt(II) plays an important role not only in promoting the H2O2 formation but also in inhibiting the H2O2 decomposition.

Deciphering the synergy between electron localization and alloying for photoelectrochemical nitrogen reduction to ammonia
Jianyun Zheng, Yanhong Lyu, Aibin Huang, Bernt Johannessen, Xun Cao, San Ping Jiang, Shuangyin Wang
2023, 45:  141-151.  DOI: 10.1016/S1872-2067(22)64178-0
Abstract ( 6 )   HTML ( 2 )   PDF (3947KB) ( 26 )  
Supporting Information

Photoelectrochemistry that directly takes advantage of solar energy by photoelectrodes is a promising green route for the nitrogen fixation, but is currently far from practical application. It is necessary to understand the structure-reactivity interplay of the photocathodes for rendering rational improvement of the existing challenges. Here, we make efforts to reveal AuCoPd-CoOx/SiO2/Si photocathodes capable of selective photoelectrochemical conversion of nitrogen to ammonia at varied pressures, achieving an ammonia yield rate of 22.2 ± 0.4 μg·h-1·cm-2 and a faradic efficiency of 22.9% at -0.1 V vs. reversible hydrogen electrode under 3-MPa nitrogen. In particular, we focus on the remarkable, but often subtle, roles of the synergy between electron localization and alloying in determining the reactivity of the photocathodes. Specifically, operando XPS and XAS illustrate that the oxidation states of Au and Pd enable the photoinduced electron capture as the reduction sites to produce the *N2 and *H active species, respectively, facilitating the couple of N-H for ammonia synthesis. Although this study is not sufficient to break through bottleneck, there is much insight on the design of efficient and robust photocathodes for photoelectrochemical nitrogen fixation.

Atomically dispersed Ni-N-C catalyst derived from NiZn layered double hydroxides for efficient electrochemical CO2 reduction
Ping Zhang, Hao Chen, Lin Chen, Ying Xiong, Ziqi Sun, Haoyu Yang, Yingke Fu, Yaping Zhang, Ting Liao, Fei Li
2023, 45:  152-161.  DOI: 10.1016/S1872-2067(22)64188-3
Abstract ( 7 )   HTML ( 3 )   PDF (8846KB) ( 25 )  
Supporting Information

Atomically dispersed catalytic metal sites anchored on N-doped carbon support catalysts (M-N-C) show great prospects for CO2 electroreduction. Here, single-layer NiZn layered double hydroxides (NiZn-LDHs) was used as a sacrificial assistant to fabricate single-Ni atom anchored on ultrathin porous carbon catalyst. NiZn-LDHs were exfoliated to single-layer by polyhydroxy compounds which took as the carbon resource in Ni-N-C, and single layer NiZn LDHs taking as the Ni resource could avoid the agglomeration of Ni atoms during calcining. The CO Faradaic efficiency (FECO) of the synthesized Ni-N-C catalyst exceeded 90% at -0.6 to -1.0 V and a FECO of 95.2% with a current density of 24 mA cm-2 at -0.9 V. This work not only provides a new method for preparing M-N-C catalysts, but also offers an effective and controllable strategy for large-scale production of high-performance single-atom catalysts.

The role of surface hydroxyls on ZnZrOx solid solution catalyst in CO2 hydrogenation to methanol
Feng Sha, Shan Tang, Chizhou Tang, Zhendong Feng, Jijie Wang, Can Li
2023, 45:  162-173.  DOI: 10.1016/S1872-2067(22)64176-7
Abstract ( 64 )   HTML ( 4 )   PDF (4289KB) ( 50 )  
Supporting Information

ZnZrOx solid solution catalyst is an excellent catalyst in methanol synthesis from CO2 hydrogenation. It is still highly aspiration to make any further improvement in catalytic performance. In this work, ZnZrOx solid solution catalyst is prepared with different methods, resulting in different surface property. The ZnZrOx solid solution catalyst prepared by reflux ammonia (ZnZrOx-RA) exhibits higher methanol selectivity of 95.2% and CO2 conversion of 3.3% than that of the catalyst obtained via co-precipitation (ZnZrOx-CP) at 280 °C, 5 MPa. Subsequent kinetics analysis shows that ZnZrOx-RA, in comparison to ZnZrOx-CP, shows a decreased activation energy for methanol synthesis, an increased reaction order in H2, and a similar reaction order in CO2. Structural characterizations indicate that these two catalysts are in solid solution state, while ZnZrOx-RA possesses more Zn-OH species on the surface. The surface Zn-OH species enhance the activation and adsorption of CO2 and H2, and improve the generation and stability of HCOO* species, which promote CO2 hydrogenation to methanol.

High-entropy alloy metallene for highly efficient overall water splitting in acidic media
Dan Zhang, Yue Shi, Xilei Chen, Jianping Lai, Bolong Huang, Lei Wang
2023, 45:  174-183.  DOI: 10.1016/S1872-2067(22)64166-4
Abstract ( 52 )   HTML ( 2 )   PDF (2355KB) ( 44 )  
Supporting Information

The preparation of stable and efficient acidic overall water splitting catalysts is crucial to advance the progress of proton exchange membrane water electrolyzers. Herein, we successfully prepared IrPdRhMoW HEA metallene with rich amorphous and crystalline structures. In 0.5 mol L-1 H2SO4, the extraordinary catalytic performance (the overpotentials for hydrogen evolution (HER) and oxygen evolution (OER) of IrPdRhMoW/C at 10 mA cm-2 are 15 mV and 188 mV, respectively) is far stronger than that of commercial catalysts (HER: Pt/C, 47 mV and OER: RuO2, 305 mV) and even other reported noble metal-based catalysts. Using IrPdRhMoW/C for the overall water splitting, only a cell voltage of 1.48 V is required to achieve 10 mA cm-2 and 1.59 V required to achieve 100 mA cm-2, which is the best voltage under high current density reported so far. More importantly, the IrPdRhMoW/C still maintains excellent electroactivity and structural stability after 100 h of water splitting at 100 mA cm-2. Theory calculations reveal the self-balanced effect of electronic structures in the HEA due to the co-existence of crystalline and amorphous lattice structures. The strong orbital couplings not only maximize the electroactivity towards both HER and OER but also stabilize the valence states of metal sites for durable electrocatalysis.