1. |
- Du, Jian, et al.
(författare)
-
Iron carbonate hydroxide templated binary metal-organic frameworks for highly efficient electrochemical water oxidation
- 2019
-
Ingår i: Chemical Communications. - : Royal Society of Chemistry. - 1359-7345 .- 1364-548X. ; 55:98, s. 14773-14776
-
Tidskriftsartikel (refereegranskat)abstract
- Metal-organic frameworks (MOFs) are promising catalysts for electrochemical reactions. Herein, self-supported NiFe-MOF nanoplates grown on Ni foam (NF) were prepared with iron carbonate hydroxide nanosheets (FeCH NSs) as a semisacrificial template and evaluated for the electrocatalytic oxygen evolution reaction (OER). In this approach, the porous FeCH NSs not only serve as the iron source of NiFe-MOF, but also slow down the leaching of Ni ions from the substrate, thus playing a unique role in regulating the morphology of NiFe-MOF with reduced thickness and sizes, enabling rapid electron transfer and mass transport. The resultant NiFe-MOF/FeCH-NF electrode showed higher activity than FeCH template-free electrodes and superior OER performance over other MOF based binder-free OER electrodes. A current density of 10 mA cm(-2) was obtained at a low overpotential of 200 mV with excellent durability in alkaline solution. Raman and TEM measurements reveal the partial transformation of NiFe-MOF to hydroxide during water oxidation.
|
|
2. |
- 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.
|
|
3. |
- 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. ; 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.
|
|
4. |
- 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.
|
|
5. |
- 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. ; 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.
|
|
6. |
- Xu, Suxian, et al.
(författare)
-
Nickel-selenide templated binary metal-organic frameworks for efficient water oxidation
- 2020
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 8:33, s. 16908-16912
-
Tidskriftsartikel (refereegranskat)abstract
- The development of highly active and stable non-precious metal electrocatalysts is of great significance for energy conversion with the oxygen evolution reaction (OER) being a rate-determining step. Herein, we report a hybrid material bearing a three-dimensional (3D) core-shell hierarchical structure, in which binary metal-organic framework nanosheets (NiFe-MOF NSs) are rationally decorated on NiSe(x)nanosheet (NS) arrays supported on Ni foam (NF). With this approach, the highly conductive NiSe(x)NSs ensure rapid charge transfer, the NiFe-MOF NSs provide a large number of exposed active sites, and the 3D hierarchical structure benefits gas release and electrolyte diffusion. As a result the NiFe-MOF/NiSex/NF electrode delivers current densities of 10 and 100 mA cm(-2)at overpotentials of 198 and 230 mV and reveals a low Tafel slope of 30.6 mV dec(-1)toward the OER. When NiFe-MOF/NiSex/NF was used as both the anode and cathode for overall water splitting, the potential to deliver a current density of 10 mA cm(-2)was 1.59 V, lower than that for the benchmark IrO2/NF(+)||Pt/C/NF(-) system (1.66 V at 10 mA cm(-2)).
|
|
7. |
- 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.
|
|