Metal–Organic Framework Based Catalysts for Hydrogen Evolution

Abstract

society is still heavily relying on chemical fuels. Therefore, the essential and realistic approaches to environmental and energy issues remain to be the exploration of clean and sustainable energy sources, in order to meet the ever-increasing energy demand. Thanks to its high energy density and environmental friendliness, hydrogen fuel comes into play as a muchanticipated new energy carrier, which is under intensive studies in the academic field. [4] Furthermore, we are already in the new era witnessing the transformation of hydrogen-powered technologies from science fictions to realities. UK is already in the process of replacing their traditional diesel-powered double decker buses with the hydrogen-powered version, which aims to phase out the former by 2018. [5] China announced its world's first hydrogen-powered tram, which was put into business service in the latter half of 2017. [6] Mercedes-Benz had even started its development of personal hydrogen-powered car, and Toyota had commercialized its hydrogen fuel-cell car branded "Mirai." [7,8] However, one critical issue remains to be the conflict between the hydrogen production efficiency and the demand for the mass distribution of hydrogen-powered technologies.Current industrial hydrogen production methods include coal gasification (followed by water-gas shift reaction), steam reforming, cryogenic distillation, and water splitting. [9] Coal gasification and steam reforming utilize the reaction between conventional fossil fuels and water to produce syngas (primarily CO and H 2 ) or CO 2 and H 2 mixture. However, both reactions require high temperatures (can be over 1000 °C) and pressures, which is an energy intensive process and has strict requirements on infrastructures. [10] The reaction products also need to be further separated to obtain relatively high-concentration of hydrogen. Cryogenic distillation takes the advantage of difference in gas boiling points, which can be applied to separate hydrogen from other gas components in the former two hydrogen production methods. However, cryogenic distillation is also an energy intensive process for low-temperature gas liquification. In comparison, hydrogen evolution reaction (HER) through water splitting is much-favored because of the following three prominent advantages: 1) Water splitting can be carried out at room temperature and ambient pressure, which is less restricted by infrastructure requirements. 2) Oxygen and hydrogen can be produced separately or selectively, which eliminate the need for gas separation. 3) Both the hydrogen source Highly efficient hydrogen evolution reactions (HERs) will determine the mass distributions of hydrogen-powered clean technologies in the future. Metal-organic frameworks (MOFs) are emerging as a class of crystalline porous materials. Along with their derivatives, MOFs have recently been under intense study for their applications in various hydrogen production techniques. MOF-based materials possess unique advantages, such as high specific surface area, crystalline porous str...

Structural Engineering of Low‐Dimensional Metal–Organic Frameworks: Synthesis, Properties, and Applications

“…[286][287][288][289][290][291] The catalytic active sites of MOF-based materials are usually originated from their coordinatively unsaturated metal sites (CUSs), and functional organic linkers. [286][287][288][289][290][291] The catalytic active sites of MOF-based materials are usually originated from their coordinatively unsaturated metal sites (CUSs), and functional organic linkers.…”

Single Atoms on Graphene for Energy Storage and Conversion

“…H 2 as a clean and renewable energy carrier is often utilized in fuel cells. Generally, the electrochemical reduction of protons (acid) or water (alkaline) is one of the most green and sustainable approach to produce H 2 through HER process . The formation and the reaction path of H* intermediate have an important role in HER process.…”

“…Therefore, the design of functional substrates is necessary to stabilize the single atoms for achieving their cycling stability in acidic electrolytes. Heteroatom‐doping graphene has been served as the substrate to disperse various kinds of single atoms by forming the strong chemical coordination MN bonds . The formation of MN bonds could effectively immobilize the single atoms on substrate and avoid their dissolution in electrolytes.…”

Designing Advanced Catalysts for Energy Conversion Based on Urea Oxidation Reaction

“…An effective clean energy technology does not only improve the efficiency of energy utilization, but also possesses the capability of remediating current environmental issues. At present, apart from renewable energy sources (e.g., wind, solar, and hydropower), hydrogen fuel is highly anticipated as promising candidates to replace traditional fossil fuels because of its high energy density and environmental friendliness . However, the promotion of hydrogen fuels heavily relies on the operating efficiencies of hydrogen production and energy conversion techniques, such as water splitting and hydrogen fuel cells .…”