Transition Metal-Based Electrocatalysts: Applications in Green Hydrogen Production and Storage

The hydrogen generation and storage are the main barriers hindering the rapid development of hydrogen economics. This chapter summarizes recent advances of transition metal-based materials in the hydrogen generation and storage via electrocatalysis. Various modifications including morphology design, heterostructure constructing, element doping and vacancies engineering are discussed in the part of hydrogen evolution to reveal the correlation among modification, structure and catalytic performance of transition metal-based materials. Moreover, light hydrogen-containing chemicals are the effective and promising hydrogen energy carriers. The progress on the transition-metal based electrocatalysts for the ammonia, methanol and ethanol production is also briefly reviewed.

Microbial electrolysis cells (MECs) have gained significant prominence as a device to generate sustainable green hydrogen. The H₂ gas produced is biohydrogen, since it is obtained from biowastes and organic matter in wastewater. However, commercialization of MECs on a pilot scale is confined due to the higher cost of Pt electrodes used. In this chapter, we have focused on cathode catalysts that could be a potential substitute to Pt catalysts in terms of hydrogen evolution reaction (HER) performance and fabrication cost. The chapter is set forth by introducing MECs, their mechanism, and functions, followed by various H₂ evolution catalysts currently in use. Great interest is given to the HER process, H₂ production ability, and the costs of various catalysts. Furthermore, environmental impacts, future challenges and perspectives in developing sustainable cost–effective catalysts for MECs have been discussed thoroughly.

Green energy economies around the world consider hydrogen to be an important component of a clean and sustainable hydrogen economy. Energy from fossil fuels is cheaper but it faces various serious consequences of global concerns. H₂ is cleanest, renewable and sustainable energy carrier that reduced significant amount of hazardous impact on the environment. It meets the ambitious targets of the reduction of greenhouse gases in the 2035-2050 timeframe. Green hydrogen production has other striking properties such as inclusive flammability and higher gravimetric energy content than other fossil fuels. The production and storage of H₂ is an important component for development of green energy technology for rise in economy of the developing countries. The evolution of hydrogen through various routes, Hydrogen storage methods and recent nano metal-based advancement in production and storage has now gain tremendous research and industrial interest globally. This comprehensive book chapter is reviewed to link the latest research progress in hydrogen production routes, hydrogen storage methods and investigate the role of nano metal-based electrocatalysts. It also contributes to improve research and develop road map for green hydrogen production and storage methods. Further more recent development and knowledge gap has been highlighted for better understanding.

For replacing non-renewable fossil fuels and to address the serious environment related issues, hydrogen is considered as the main candidate for green energy. Studies are going on worldwide for developing technologies that produce hydrogen energy, such as, water splitting, fuel cells, etc. The large-scale production of hydrogen energy using electrocatalytic water splitting is an environmentally friendly technology. This system involves several important reactions; mainly hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Both these reactions require highly active and stable electrocatalysts. In this chapter, we summarize the fundamentals of HER, OER and some of the recent developments on OER and HER electrocatalysts and the strategies for improving the performance of these electrocatalysts.

Hydrogen is a promising and non-polluting energy carrier. Hydrogen production and storage is one of the important research activities in both industrial and scientific community that can address several concerns connected to sustainability and efficiency. This chapter discusses the role of analytical techniques especially Raman spectroscopy techniques in hydrogen production and storage. First, a general overview of hydrogen production pathways and the basics of Raman spectroscopy are discussed. Then, the application of Raman and plasmon-enhanced Raman spectroscopies in catalyst characterization, hydrogen storage and production are highlighted. Finally, challenges and future directions are also discussed.

The hydrogen spillover effect (HSPE) is an appealing interfacial phenomenon in the hydrogen evolution reaction (HER). However, the application of HSPE in transition metal-based electrocatalytic materials is still at an exploratory stage due to the unclear reaction mechanism and the complex electrolytic environment. How to apply the HSPE as a functionalized strategy for designing efficient electrocatalytic materials becomes the research focus. In order to better understand the role of HSPE in electrocatalytic water splitting, this chapter first introduces the basic principles of HSPE, followed by a review of electrocatalysts utilizing HSPE in acidic and alkaline electrolysis. The underlying mechanism of HSPE for improving the HER performance and the designing principles of HER catalysts are then analyzed. Lastly, the present issues in this research area and the promising research directions are proposed. Hopefully, this chapter can provide meaningful guidance for designing cost-effective and efficient HER electrocatalysts by applying the HSPE.

Considering the huge motivating, ongoing research on the upcoming hydrogen economy, the present chapter discusses green/renewable production of hydrogen to be used as environmentally benign fuel. The most popular electrocatalytic hydrogen evolution is discussed as the most significant and approachable path for green hydrogen production. Transition metal electrocatalysts are reviewed, focusing on their properties, synthesis, and catalytic activities. Different strategies to increase the electrocatalytic efficiency for hydrogen evolution reactions are recalled. Essential methods of green hydrogen production using renewable energy sources solar light are mentioned. Photocatalytic (PC), Photoelectrochemical (PEC), and Photovoltaic electrochemical (PV-EC) water splitting methods are explained with examples. Hydrogen purification using membrane methods has been discussed. The future aspects as well as the applications and storage of green hydrogen are also included in the chapter.

The reliance on fossil fuels has not only led to large-scale industrial development but also significant depletion of natural resources and negative effects on climate. Recently, renewable sources have been used for biohydrogen (H2) production as a clean bioenergy. A variety of biological routes were developed to produce biohydrogen production. This chapter aims to discuss biocatalysts to produce biohydrogen. Here, an attempt was made to discuss various catalysts for biohydrogen production. Moreover, an effort was made to discuss diverse microbes as biocatalysts for biohydrogen production. Also, the pretreatment of biocatalysts for biohydrogen production is highlighted. Furthermore, immobilized biocatalysts were elaborated for biohydrogen production. Finally, conclusions and future recommendations were emphasized for biohydrogen production using biocatalysts.

The increasing population and economic growth of developed and developing countries have increased global energy demand, and so increasing pursuits have been carried out to search for renewable energy sources. Hydrogen plays a key role as a green energy carrier for the future owing to its low volumetric and high gravimetric energy content, zero carbon emission, and earth-abundance. However, the high costs are a significant obstacle to the commercialization of these systems. Generally, high-cost noble metals are used as catalysts in hydrogen production. Therefore, inexpensive catalyst research is one of the main pathways for reducing system costs of hydrogen production. Transition metal-based are among the more accessible materials because of their abundance worldwide. This chapter highlights the use of transition metal-based catalysts like Ni, Cu, Co, Fe, and other transition metals as an alternative to precious metal catalysts for acidic and alkaline media. It discusses the performance of elemental and composite forms of transition metal-based alkaline and acidic electrochemical systems.

Given its present reputation as the most environmentally friendly energy source, hydrogen is a foremost contender to displace fossil fuels and address the world’s environmental and energy subjects. In fact, scientists are working to create a range of devices for the consumption and conversion of hydrogen energy, including fuel cells, photocatalytic, and electrocatalytic water splitting. On a vast scale, clean and pure hydrogen can be formed from water by electrocatalytically splitting with the use of electric energy. This hydrogen can then be immediately converted into energy using fuel cells. The hydrogen evolution reaction (HER) and theoxygen reduction reaction (ORR), both of which necessitate powerful electrocatalysts with great efficiency, are two of the critical reactions that are necessary for this ecologically advantageous system to function. Despite the scientific community’s enormous efforts, there are still no electrocatalysts that work properly. The functionality of electrocatalysts, namely their active sites, is crucial. An important way to raise the administration of electrocatalysts is by active site engineering, which entails changing the catalysts’ active site characteristics. Altering the surroundings and altering the active sites’ structures are two common active site engineering strategies. These methods can be used to speed up the entire reaction process to improve the electrical characteristics of the active sites. To improve electrocatalytic HER performance, in general, researchers construct transition metal (TMs)-based electrocatalysts. Thus, this chapter will go through how improving hydrogen evolution catalysis can be offered by the help ofTMs electrocatalysts. Further discussion will be about the active site modifications that can improve the catalytic activity of the active sites by tuning surface atomic configurations, and changing heteroatoms attached to the TMs. This chapter emphasizes reliable methods for designing effective active sites in electrocatalysts based on transition metals. These methods might present fresh chances for the rational strategy and creation of effective electrocatalysts for numerous energy utilization.