| 1. |
- Xu, Suxian, et al.
(författare)
-
Immobilization of Iron Phthalocyanine on Pyridine-Functionalized Carbon Nanotubes for Efficient Nitrogen Reduction Reaction
- 2022
-
Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435 .- 2155-5435. ; 12:9, s. 5502-5509
-
Tidskriftsartikel (refereegranskat)abstract
- An electrochemical nitrogen reduction reaction (NRR) under mild conditions offers a promising alternative to the traditional Haber-Bosch process in converting abundant nitrogen (N2) to high value-added ammonia (NH3). In this work, iron phthalocyanine (FePc) was homogeneously immobilized on pyridine-functionalized carbon nanotubes to form a well-tuned electrocatalyst with an FeN5 active center (FePc-Py-CNT). Synchrotron X-ray absorption and Fourier transform infrared spectroscopy proved the presence of an Fe-N coordination bond between FePc and surface-bound pyridine. The resulting hybrid exhibited notably enhanced electrocatalytic NRR performance compared to FePc immobilized on CNTs based on pi-pi stacking interactions (FePc-CNT), resulting in doubled NH3 yield (21.7 mu g 1 h mgcat-1h-1) and Faradaic efficiency (22.2%). Theoretical calculations revealed that the axial coordination on FePc resulted in partial electron transfer from iron to pyridine, which efficiently suppresses the adsorption of H+ and improves the chemisorption of N2 at Fe sites. Meanwhile, the interfacial electron transfer was facilitated by pyridine as an electron transfer relay between FePc and CNTs. This work provides a unique strategy for the design of highly efficient NRR electrocatalysts at the molecular level.
|
|
| 2. |
- Xu, Suxian, et al.
(författare)
-
Polystyrene spheres-templated mesoporous carbonous frameworks implanted with cobalt nanoparticles for highly efficient electrochemical nitrate reduction to ammonia
- 2023
-
Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 323
-
Tidskriftsartikel (refereegranskat)abstract
- Electrocatalytic nitrate reduction reaction (eNO3RR) to ammonia (NH3) provides an intriguing approach for both environmental denitrification and sustainable NH3 synthesis. Herein, we report the fabrication of hierarchically mesoporous Co nanoparticles decorated N-doped carbon composites as a highly efficient electrocatalyst for eNO3RR by using monodispersed polystyrene spheres (PS) as sacrificial templates (MR Co-NC). By taking advantage of the large specific area of the pore-rich structures and the high intrinsic activity of metallic Co, the MR Co-NC shows remarkable activity toward eNO3RR, which achieves a partial current density of 268 mA cm-2 with a Faradaic efficiency (FE) of 95.35 +/- 1.75 % and a generation rate of 1.25 +/- 0.023 mmol h-1 cm-2 for NH3 production under the optimal conditions. The porous carbon skeleton was found to play a dual role by simul-taneously protecting the active sites from oxidation and facilitating long-range charge and mass transfer. Theoretical calculations reveal a lower energy barrier of the rate-determining step (*NO2 + H2O + 2e- -> *NO + 2OH-) on the metallic Co of MR Co-NC over beta-Co(OH)2 formed by the reconstruction of carbon-free Co nanoparticles.
|
|
| 3. |
- Du, Jian, et al.
(författare)
-
Iron-Salen Complex and Co2+ Ion-Derived Cobalt-Iron Hydroxide/Carbon Nanohybrid as an Efficient Oxygen Evolution Electrocatalyst
- 2019
-
Ingår i: Advanced Science. - : WILEY. - 2198-3844. ; 6:12
-
Tidskriftsartikel (refereegranskat)abstract
- Metal-salen complexes are widely used as catalysts in numerous fundamental organic transformation reactions. Here, CoFe hydroxide/carbon nanohybrid is reported as an efficient oxygen evolution electrocatalyst derived from the in situ formed molecular Fe-salen complexes and Co2+ ions at a low temperature of 160 degrees C. It has been evidenced that Fe-salen as a molecular precursor facilitates the confined-growth of metal hydroxides, while Co2+ plays a critical role in catalyzing the transformation of organic ligand into nanocarbons and constitutes an essential component for CoFe hydroxide. The resulting Co1.2Fe/C hybrid material requires an overpotential of 260 mV at a current density of 10 mA cm(-2) with high durability. The high activity is contributed to uniform distribution of CoFe hydroxides on carbon layer and excellent electron conductivity caused by intimate contact between metal and nanocarbon. Given the diversity of molecular precursors, these results represent a promising approach to high-performance carbon-based water splitting catalysts.
|
|
| 4. |
- Li, Jiayuan, et al.
(författare)
-
Dye-sensitized photoanode decorated with pyridine additives for efficient solar water oxidation
- 2021
-
Ingår i: Cuihuà xuébào. - : Elsevier BV. - 0253-9837 .- 1872-2067. ; 42:8, s. 1352-1359
-
Tidskriftsartikel (refereegranskat)abstract
- Splitting water into hydrogen and oxygen by dye-sensitized photoelectrochemical cell (DSPEC) is a promising approach to solar fuels production. In this study, a series of pyridine derivatives as surface additives were modified on a molecular chromophore and water oxidation catalyst co-loaded TiO2 photoanode, TiO2 vertical bar RuP, 1 (RuP = Ru(4,4'-(PO3H2)(2)-2,2'-bipyridine)(2,2'-bipyridine)2, 1 = Ru(bda)(L)(2), (bda = 2,2'-bipyridine-6,6'-dicarboxylate, L = 10-(pyridin-4-yloxy)decyl)phosphonic acid). The addition of pyridine additives was found to result in up to 42% increase in photocurrent. Under simulated sun-light irradiation, TiO2 vertical bar RuP, 1, P-1 (P-1 = 4-Hydroxypyridine) produced a photo-current density of 1 mA/cm(2) at a bias of 0.4 V vs. NHE in acetate buffer. Moreover, the observed photocurrents are correlated with the electron-donating ability of the substituent groups on pyridine ring. Transient absorption measurements and electrochemical impedance spectroscopy revealed that surface-bound pyridine can effectively retard the back-electron transfer from the TiO2 conduction band to the oxidized dye, which is a major process responsible for energy loss in DSPECs.
|
|
| 5. |
- Liu, Guoquan, et al.
(författare)
-
Cobalt doped BiVO(4)with rich oxygen vacancies for efficient photoelectrochemical water oxidation
- 2020
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 10:48, s. 28523-28526
-
Tidskriftsartikel (refereegranskat)abstract
- A facile electrodeposition method was developed to prepare Co-BiVO(4)thin films with rich oxygen vacancies. The resulting photoanode exhibited a photocurrent density of 3.5 mA cm(-2)1.23 V (vs.reversible hydrogen electrode (RHE), AM 1.5 G), which is over two times higher than that of undoped BiVO4.
|
|
| 6. |
- Liu, Guoquan, et al.
(författare)
-
Photocatalytic Water Oxidation by Surface Modification of BiVO4 with Heterometallic Polyphthalocyanine
- 2023
-
Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435 .- 2155-5435. ; 13:13, s. 8445-8454
-
Tidskriftsartikel (refereegranskat)abstract
- Developing efficient photocatalysts for water oxidation is among the central challenges of solar energy conversion. Here, we report semiconductor-molecular photocatalysts by integration of heteronuclear bimetallic polyphthalocyanine (PPc) catalysts with particulate bismuth vanadate (BiVO4) as the photosensitizer. Their photocatalytic activity for water oxidation was modulated by tuning the Fe/Co ratio of polyphthalocyanines. At an optimal Fe/Co ratio of 3:1, the resulting Fe3CoPPc-BiVO4 hybrid exhibits an excellent oxygen evolution rate of 4557 μmol g-1 h-1 in the presence of iodate under visible light irradiation, which is nearly two orders of magnitude greater than that of pristine BiVO4 and superior to those of the corresponding homometallic counterparts. Both experimental and theoretical methods suggest that the presence of a large population of high-valent Fe/Co molecular species due to the favorable interfacial charge transfer and upshift of the d-band centers of metal sites toward Fermi level lead to a lower energy barrier for the O-O bond formation and eventually promote the oxidation of water.
|
|
| 7. |
- Wen, Zhibing, et al.
(författare)
-
Aqueous CO2 Reduction on Si Photocathodes Functionalized by Cobalt Molecular Catalysts/Carbon Nanotubes
- 2022
-
Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 61:24
-
Tidskriftsartikel (refereegranskat)abstract
- Photoelectrochemical reduction of CO2 is a promising approach for renewable fuel production. We herein report a novel strategy for preparation of hybrid photocathodes by immobilizing molecular cobalt catalysts on TiO2-protected n+-p Si electrodes (Si|TiO2) coated with multiwalled carbon nanotubes (CNTs) by π–π stacking. Upon loading a composite of CoII(BrqPy) (BrqPy=4′,4′′-bis(4-bromophenyl)-2,2′ : 6′,2′′ : 6′′,2′′′-quaterpyridine) catalyst and CNT on Si|TiO2, a stable 1-Sun photocurrent density of −1.5 mA cm−2 was sustained over 2 h in a neutral aqueous solution with unity Faradaic efficiency and selectivity for CO production at a bias of zero overpotential (−0.11 V vs. RHE), associated with a turnover frequency (TOFCO) of 2.7 s−1. Extending the photoelectrocatalysis to 10 h, a remarkable turnover number (TONCO) of 57000 was obtained. The high performance shown here is substantially improved from the previously reported photocathodes relying on covalently anchored catalysts.
|
|
| 8. |
- Yu, Suxian, et al.
(författare)
-
Modulating the proton transfer kinetics via Ru single atoms for highly efficient ammonia synthesis
- 2023
-
Ingår i: Chem Catalysis. - : Elsevier BV. - 2667-1107 .- 2667-1093. ; 3:9
-
Tidskriftsartikel (refereegranskat)abstract
- The electrochemical nitrate reduction reaction (eNO3RR) is an appealing technology for converting environmentally toxic NO3− to ammonia (NH3). This approach was usually obstructed by the multi-proton/electron involved process. Here, we report a catalyst with Ru single atoms supported on Co3O4 (Ru SAs-Co3O4). The as-developed Ru SAs-Co3O4 catalyst shows a remarkable NH3-evolving activity with a faradic efficiency of 94.92% ± 4.02% at the potential of −0.2 V (vs. RHE) and a generation rate of 1,843.45 ± 57.14 μmol h−1 cm−2 at the potential of −0.5 V. Further investigations revealed that the Ru SAs play a dual role in simultaneously accelerating the proton transfer and modulating the d-electron structures of the neighboring Co sites, which led to a lower energy barrier of the rate-determining step. Eventually, by combining the eNO3RR and electrosynthesis of 5,5′-azotetrazolate at a two-electrode system, an energy-saving NH3 synthesis, while simultaneously producing value-added chemicals, was successfully achieved.
|
|
