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•Nickel-based molecular catalysts for electrocatalytic and photocatalytic hydrogen evolution reaction.•Nickel-based molecular catalysts for electrocatalytic and photocatalytic oxygen ...evolution reaction.•Nickel-based molecular catalysts for electrocatalytic and photocatalytic carbon dioxide reduction.
One of the most appealing strategies to address the problems of global warming and energy shortage is to develop clean and sustainable energy source. To this end, considerable efforts have been devoted to designing well-defined catalysts for energy conversion. As an earth-abundant transition metal, nickel has been regarded to be an important catalytic center in molecular catalysts for redox reactions related to energy conversion. This Review focuses on the properties of nickel complexes as molecular catalysts in energy conversion driven by electricity or light, including water splitting and carbon dioxide (CO2) reduction.
Covalent organic frameworks (COFs) have been widely studied in photocatalytic CO2 reduction reaction (CO2RR). However, pristine COFs usually exhibit low catalytic efficiency owing to the fast ...recombination of photogenerated electrons and holes. In this study, we fabricated a stable COF‐based composite (GO‐COF‐366‐Co) by covalently anchoring COF‐366‐Co on the surface of graphene oxide (GO) for the photocatalytic CO2 reduction. Interestingly, in absolute acetonitrile (CH3CN), GO‐COF‐366‐Co shows a high selectivity of 94.4 % for the photoreduction of CO2 to formate, with a formate yield of 15.8 mmol/g, which is approximately four times higher than that using the pristine COF‐366‐Co. By contrast, in CH3CN/H2O (v : v=4 : 1), the main product for the photocatalytic CO2 reduction over GO‐COF‐366‐Co is CO (96.1 %), with a CO yield as high as 52.2 mmol/g, which is also approximately four times higher than that using the pristine COF‐366‐Co. Photoelectrochemical experiments demonstrate the covalent bonding of COF‐366‐Co and GO to form the GO‐COF‐366‐Co composite facilitates charge separation and transfer significantly, thereby accounting for the enhanced catalytic activity. In addition, theoretical calculations and in situ Fourier transform infrared spectroscopy reveal H2O can stabilize the *COOH intermediate to further form a *CO intermediate via O−H(aq)⋅⋅⋅O(*COOH) hydrogen bonding, thus explaining the regulated photocatalytic performance.
The photocatalytic performance for the reduction of CO2 to HCOO− or CO can be significantly enhanced by covalently anchoring COF‐366‐Co on the surface of graphene oxide.
There is a demand to develop molecular catalysts promoting the hydrogen evolution reaction (HER) with a high catalytic rate and a high tolerance to various inhibitors, such as CO and O2. Herein we ...report a cobalt catalyst with a penta‐dentate macrocyclic ligand (1‐Co), which exhibits a fast catalytic rate (TOF=2210 s−1) in aqueous pH 7.0 phosphate buffer solution, in which proton transfer from a dihydrogen phosphate anion (H2PO4−) plays a key role in catalytic enhancement. The electrocatalyst exhibits a high tolerance to inhibitors, displaying over 90 % retention of its activity under either CO or air atmosphere. Its high tolerance to CO is concluded to arise from the kinetically labile character of undesirable CO‐bound species due to the geometrical frustration posed by the ligand, which prevents an ideal trigonal bipyramid being established.
Highly tolerant: A cobalt(II) complex of a pentadentate ligand can efficiently electrocatalyze hydrogen evolution in an aqueous phosphate buffer at pH 7.0, affording a fast catalytic rate of 2210 s−1. This complex has a high tolerance to both CO and air, displaying over 90 % retention of its catalytic activity under CO‐ and air‐saturated conditions.
A catalyst developed from a CuII complex of (Et4N)Cu(pyN2Me2)(HCO2)⋅0.5 CH3OH⋅H2O (1⋅0.5 CH3OH⋅H2O; pyN2Me2=bis(2,6‐dimethylphenyl)‐2,6‐pyridinedicarboxamidate(2‐)) shows a high activity to catalyze ...the reduction reaction of CO2 to CO driven by visible light in 4:1 acetonitrile/water (v:v) using Ru(phen)3(PF6)2 as photosensitizer and TEOA as sacrificial reductant, with a high TON of 9900 and a high CO selectivity of 98 %. The results of isotope labeling experiment, durability tests and energy dispersive spectroscopy reveal that 1 is robust during the photocatalytic process.
Your Highness! A catalyst developed from a CuII complex shows a high activity to catalyze the reduction reaction of CO2 to CO in 4:1 acetonitrile/water (v:v) using Ru(phen)3(PF6)2 as photosensitizer and TEOA as sacrificial reductant, with a high TON of 9900 and a high CO selectivity of 98 %.
Homonuclear dual‐atomic catalysts showcase unique electronic modulation due to their dual metal centres, providing new direction in development of efficient catalysts for CO2 electroreduction. This ...article highlights a few cutting‐edge homonuclear dual‐atomic catalysts, focusing on their inherent advantages in efficient and selective CO2 electroreduction, to spotlight the potential application of dual‐atomic catalysts in CO2 electroreduction.
Homonuclear dual‐atomic catalysts showcase unique electronic modulation due to their dual metal centres. This configuration presents a promising avenue in the realm of electrocatalytic reduction of CO2 to CO.
Facile synthesis of photocatalysts with highly dispersed metal centers is a high-priority target yet still a significant challenge. In this work, a series of Co-C
3
N
4
photocatalysts with different ...Co contents atomically dispersed on g-C
3
N
4
have been prepared via one-step thermal treatment of cobalt-based metal-organic frameworks (MOFs) and urea in the air. Thanks to the highly dispersed and rich exposed Co sites, as well as good charge separation efficiency and abundant mesopores, the optimal 25-Co-C
3
N
4
, in the absence of noble metal catalysts/sensitizers, exhibits excellent performance for photocatalytic CO
2
reduction to CO under visible light irradiation, with a high CO evolution rate of 394.4 µmol·g
−1
·h
−1
, over 80 times higher than that of pure g-C
3
N
4
(4.9 µmol·g
−1
·h
−1
). In addition, by this facile synthesis strategy, the atomically dispersed Fe and Mn anchoring on g-C
3
N
4
(Fe-C
3
N
4
and Mn-C
3
N
4
) have been also obtained, indicating the reliability and universality of this strategy in synthesizing photocatalysts with highly dispersed metal centers. This work paves a new way to develop cost-effective photocatalysts for photocatalytic CO
2
reduction.
Coordination polymers (CPs) are ideal precursors for synthesizing porous catalysts. However, the direct thermolysis of CPs is prone to generate agglomerates, greatly reducing the electrical ...conductivity and active sites of their derived catalysts. The construction of well‐ordered CP nanostructures is a promising strategy for alleviating the above issue, but it remains challenging. Here, a facile chemical etching approach is developed for the fabrication of well‐aligned three‐dimensional (3D) bimetallic Prussian blue‐analogue nanosheet arrays. Impressively, the derived porous metal oxide (Fe–NiO) acts as a remarkable oxygen evolution reaction (OER) catalyst, which merely requires overpotentials as low as 218 and 270 mV to achieve 10 and 100 mA cm−2 in 1.0 m KOH aqueous solution, respectively. The excellent electrocatalytic performance of Fe–NiO is ascribed to the 3D porous nanosheet array architecture, which endows the bimetallic catalyst with abundant electrocatalytic active sites, enhanced surface permeability, and high electronic conductivity. It is expected that the proposed strategy can pave a new way for fabricating highly efficient electrocatalysts for energy storage and conversion.
A piece of art: Well‐ordered 3D bimetallic Prussian blue analogue nanosheet arrays are fabricated by etching Ni(OH)2 nanosheet arrays with potassium ferricyanide. The derived porous electrocatalyst exhibits excellent electrochemical activity and stability for the oxygen evolution reaction with overpotentials as low as 218 and 270 mV to achieve 10 and 100 mA cm−2 in 1.0 m KOH solution, respectively.
Using an experimental approach, the role of metal catalysis has been investigated in the in situ cycloaddition reaction of nitrile with azide to form tetrazoles. It has been shown that metal ...catalysis serves to activate the cyano group in the nitrile reagent by a coordinative interaction.
A key role: Using an experimental approach, the role of metal catalysis has been investigated in the in situ cycloaddition reaction of nitrile with azide to form tetrazoles. X‐ray crystallography and IR spectroscopy are used to show that the metal species acts as a catalyst, activating the cyano group in the nitrile‐containing reagent by a coordinative interaction.
The photochemical reduction of carbon dioxide (CO2) into valuable chemicals or feedstock is very meaningful for environmental and energy sustainability. Development of efficient, robust and low-cost ...catalysts is necessary and desirable for their practical application. In this communication, we exploited such a catalyst by anchoring single-Co(II) sites on g-C3N4, which was firstly achieved by the pyrolysis of ultrathin cobalt metal-organic framework (MOF) nanosheets (also called metal-organic layers; MOLs) during the process of g-C3N4 formation. Benefitting from the confinement effect of MOL matrix and the close contact between MOLs and g-C3N4 precursor, the Co(II) sites can be homogeneously and atomically dispersed on the surface of g-C3N4 during the process of g-C3N4 formation. Impressively, this photocatalyst possesses excellent catalytic performance for photochemical CO2-to-CO conversion, with the CO evolution rate as high as 464.1 μmol g−1 h−1, 3 and 222 times higher than those of using bulky Co-MOF and CoCl2 as the cobalt sources, respectively. This work paves a new way to develop the cost-effective photocatalysts containing single-atom sites for clean energy production.
With exposed active sites orderly confined on the surface, metal-organic layers are found to be ideal metal-source precursors used to prepare g-C3N4-based single-atom photocatalysts for efficiently catalyzing CO2 reduction. Display omitted
•A ligand replacement approach was developed for the large-scale production of 2D monolayer MOLs from general 3D MOFs.•The resulted 2D monolayer MOLs were used as precursors for the preparation of C3N4-based single-atom photocatalysts.•The cheap photocatalysts exhibited excellent catalytic performance for photochemical CO2 reduction.•The structure-activity relationship was investigated and revealed experimentally.
Revealing the contribution of π-π stacking interactions in supramolecular assembly is important for understanding the intrinsic nature of molecular assembly fundamentally. However, because they are ...much weaker than covalent bonds, π-π stacking interactions are usually ignored in the construction of porous materials. Obtaining stable porous materials that are only dependent on π-π stacking interactions, despite being very challenging, could address this concern. Here, we present a porous supramolecular framework (
) stabilized only by intermolecular π-π stacking interactions.
shows good thermal and chemical stability not only in various organic solvents but also in aqueous solution in a broad pH range. Furthermore, featuring one-dimensional channels with dangling thiolate groups,
exhibits excellent Hg
removal performance, with adsorption capacity as high as 786.67 mg g
and an adsorption ratio as high as 99.998%. In addition,
also shows high adsorption selectivity to Hg
in the presence of a series of interfering ions.
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