Metal–organic frameworks (MOFs) are composed of particles with 3D geometry and are currently among the most widely studied heterogeneous catalysts. To further increase their activity, one of the ...recent trends is to develop related 2D materials with a high aspect ratio derived from a large lateral size and a small thickness. Here, the use of these 2D MOFs as catalysts, electrocatalysts, and photocatalysts is summarized, illustrating the advantages of these 2D materials compared to analogous 3D MOFs. The state of the art is summarized in tables and, when possible, pertinent turnover number (TON) and frequency (TOF) values. This enhanced activity of 2D MOFs derives from the accessibility of the active sites, the presence of a higher density of defects, and exchangeable coordination positions around the MOFs, as well as from their ability to form thin films on electrodes or surfaces. The importance of providing convincing evidence of the stability of 2D MOFs under reaction conditions and general characterization data of the used 2D material after catalysis is highlighted. In the last part, views regarding challenges in the field and new developments that can be expected are presented.
2D MOFs often exhibit higher catalytic activity compared to their respective 3D solids due to the absence of diffusion limitation to reach active sites, easy accessibility to active sites, and high population of active sites. The use of these 2D MOFs as catalysts, electrocatalysts, and photocatalysts is reviewed, illustrating their advantages compared to the analogous 3D MOFs.
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Metal–organic frameworks (MOFs) are crystalline porous materials formed from bi‐ or multipodal organic linkers and transition‐metal nodes. Some MOFs have high structural stability, combined with ...large flexibility in design and post‐synthetic modification. MOFs can be photoresponsive through light absorption by the organic linker or the metal oxide nodes. Photoexcitation of the light absorbing units in MOFs often generates a ligand‐to‐metal charge‐separation state that can result in photocatalytic activity. In this Review we discuss the advantages and uniqueness that MOFs offer in photocatalysis. We present the best practices to determine photocatalytic activity in MOFs and for the deposition of co‐catalysts. In particular we give examples showing the photocatalytic activity of MOFs in H2 evolution, CO2 reduction, photooxygenation, and photoreduction.
MOFs, filling up with sun: Metal–organic frameworks (MOFs) can be constructed from light‐absorbing units—organic linkers and metal complexes—thus offering the possibility of photoexcitation and charge separation. The advantages of using MOFs in photocatalysis, in particular in H2 evolution and CO2 reduction, are discussed.
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In this communication, we report that a Co-doped NiSe2 nanoparticles film electrodeposited on a conductive Ti plate (Co0.13Ni0.87Se2/Ti) behaves as a robust electrocatalyst for both HER and OER in ...strongly basic media, with good activity over a NiSe2/Ti counterpart. This Co0.13Ni0.87Se2/Ti catalytic electrode delivers 10 mA cm(-2) at an overpotential of 64 mV for HER and 100 mA cm(-2) at an overpotential of 320 mV for OER in 1.0 M KOH. A voltage of only 1.62 V is required to drive 10 mA cm(-2) for the two-electrode alkaline water electrolyzer using Co0.13Ni0.87Se2/Ti as an anode and cathode.
Metal organic frameworks (MOFs) are porous crystalline solids whose structure is formed by metal ions or clusters of a few metal ions held in place by bi- or multipodal organic linkers. In some ...cases, the metal nodes in MOFs have exchangeable coordination positions that allow them to participate as active sites promoting organic reactions. There is much current interest in exploiting the advantages that MOFs offer as catalysts, including a large surface area, high metal content, flexibility in the design of the active sites in the framework, together with the easy synthesis of these materials. In the present review we describe the use of MOFs as catalysts to promote cross-coupling reactions involving organometallic reaction intermediates and catalysis by Lewis acid sites. These types of reactions are of large synthetic utility due to the high yields achieved, mild conditions and compatibility with other functional groups. The content includes C-C bond forming reactions, such as Suzuki-Miyaura, Mizoroki-Heck, Sonogashira, Stille and Ullmann, but also C-O and C-N cross-couplings. The final section summarizes our views on future developments and targets in these types of reactions. The core of the review is references that have appeared in 2010 or after, which give an idea of the novelty and current interest in this area.
This critical review aims to illustrate the recent developments in the field of C-C and C-X (X = O, N) coupling reactions promoted by metal-organic frameworks.
In this Communication, we report the topotactic fabrication of self-supported nanoporous cobalt phosphide nanowire arrays on carbon cloth (CoP/CC) via low-temperature phosphidation of the ...corresponding Co(OH)F/CC precursor. The CoP/CC, as a robust integrated 3D hydrogen-evolving cathode, shows a low onset overpotential of 38 mV and a small Tafel slope of 51 mV dec–1, and it maintains its catalytic activity for at least 80 000 s in acidic media. It needs overpotentials (η) of 67, 100, and 204 mV to attain current densities of 10, 20, and 100 mA cm–2, respectively. Additionally, this electrode offers excellent catalytic performance and durability under neutral and basic conditions.
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Searching for inexpensive hydrogen evolution reaction (HER) electrocatalysts with high activity has attracted considerable research interest in the past years. Reported herein is the topotactic ...fabrication of self‐supported Cu3P nanowire arrays on commercial porous copper foam (Cu3P NW/CF) from its Cu(OH)2 NW/CF precursor by a low‐temperature phosphidation reaction. Remarkably, as an integrated three‐dimensional hydrogen‐evolving cathode operating in acidic electrolytes, Cu3P NW/CF maintains its activity for at least 25 hours and exhibits an onset overpotential of 62 mV, a Tafel slope of 67 mV dec−1, and a Faradaic efficiency close to 100 %. Catalytic current density can approach 10 mA cm−2 at an overpotential of 143 mV.
Down to the wire: Self‐supported Cu3P nanowire arrays on porous copper foam (Cu3P NW/CF) were derived from topotactic low‐temperature phosphidation of its Cu(OH)2 NW/CF precursor. As an integrated hydrogen‐evolving cathode, Cu3P NW/CF exhibits excellent catalytic activity and durability with nearly 100 % Faradaic efficiency in acidic aqueous electrolytes.
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A closely interconnected network of MoP nanoparticles (MoP‐CA2) with rich nanopores, large specific surface area, and high conductivity can function as a highly active non‐noble metal catalyst for ...electrochemically generating hydrogen from acidic water. The network exhibits nearly 100% Faradaic efficiency and needs overpotentials of 125 and 200 mV to attain current densities of 10 and 100 mA cm−2, respectively. The catalytic activity is maintained for at least 24 h.
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Water electrolysis is considered as the most promising technology for hydrogen production. Much research has been devoted to developing efficient electrocatalysts for hydrogen production via the ...hydrogen evolution reaction (HER) and oxygen production via the oxygen evolution reaction (OER). The optimum electrocatalysts can drive down the energy costs needed for water splitting via lowering the overpotential. A number of cobalt (Co)‐based materials have been developed over past years as non‐noble‐metal heterogeneous electrocatalysts for HER and OER. Recent progress in this field is summarized here, especially highlighting several important bifunctional catalysts. Various approaches to improve or optimize the electrocatalysts are introduced. Finally, the current existing challenges and the future working directions for enhancing the performance of Co‐implicated electrocatalysts are proposed.
Electrochemical water splitting is a well‐established technology with which to produce high‐purity hydrogen. Recent progress in cobalt‐based heterogeneous electrocatalysts for water splitting is reviewed. Strategies to obtain optimized or enhanced performance are introduced through specific examples. The current existing challenges and future working directions for enhancing the performance of Co‐implicated electrocatalysts are discussed.
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Alkaline water electrolysis offers a simple method for mass production of hydrogen but suffers from the sluggish kinetics of the anodic oxygen evolution reaction (OER), calling for the development of ...low-cost and durable oxygen evolution electrocatalysts with high activity. In this communication, we report a highly-active robust oxygen evolution electrode, developed by in situ hydrothermal growth of an Fe-doped NiSe nanoflake array directly on a macroporous FeNi foam (Fe-NiSe/FeNi foam). This electrode catalyzes the OER with an onset overpotential as low as 200 mV and needs overpotentials of 245 and 264 mV to achieve 50 and 100 mA cm(-2), respectively, in 1.0 M KOH. Remarkably, it is also highly robust to drive 500 and 1000 mA cm(-2) at overpotentials of 246 and 263 mV, respectively, in 30 wt% KOH.
An Fe‐doped CoP nanoarray behaves as a robust 3D monolithic multifunctional catalyst for electrolytic and hydrolytic hydrogen evolution with high activity. Its two‐electrode electrolyzer needs a cell ...voltage of only 1.60 V for 10 mA cm−2 water‐splitting current. It also catalyzes effectively NaBH4 hydrolysis with a low activation energy of ≈39.6 kJ mol−1 and a hydrogen generation rate of 6.06 L min−1 g−1.
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