Written and edited by top fuel cell catalyst scientists and engineers from both industry and academia, this is the first book to provide a complete overview of this hot topic. It covers the synthesis, characterization, activity validation and modeling of different non-noble metal electrocatalysts, as well as their integration into fuel cells and their performance validation, while also discussing those factors that will drive fuel cell commercialization. With its well-structured approach, this is a must-have for researchers working on the topic, and an equally valuable companion for newcomers to the field.

This book introduces the reader to the state of the art in nanostructured anode and cathode electrocatalysts for low-temperature acid and alkaline fuel cells. It explores the electrocatalysis of anode (oxidation of organic molecules) and cathode (oxygen reduction) reactions. It also offers insights into metal-carbon interactions, correlating them with the catalytic activity of the electrochemical reactions. The book explores the electrocatalytic behaviour of materials based on noble metals and their alloys, as well as metal-metal oxides and metal-free nanostructures. It also discusses the surface and structural modification of carbon supports to enhance the catalytic activity of electrocatalysts for fuel-cell reactions.

Fuel cell is a device that can directly convert the chemical energy in fuels into electricity and it has the advantages including high efficiency, high energy density and zero waste emission. However, a current fuel cell requires noble-metal catalysts (in most cased platinum, Pt) to accelerate the electrode reactions. As a result of the high cost of Pt, the commercialization of fuel cell has been severely hindered. Thus, it is exceptionally important to search for an alternative low-cost catalyst, especially on the cathode when the sluggish oxygen reduction reaction (ORR) occurs and much larger amount of Pt is employed, to bring down the over-all price of a fuel cell. With this aim, this Ph.D thesis has demonstrated the design and synthesis of a serial of high -performance Pt-free catalysts based on carbon materials. These researches include: (1) We firstly designed and constructed a series of porous g-C3N4/C composite with different pore size ranging from large mesopores (ca. 12 nm) to large macropores (ca. 400 nm) and studied the structural impact of these hybrid materials on their ORR performance. In this study, we have for the first time revealed that macropores would be more favorable for ORR in such materials rather than the conventionally believed mesopores. (2) Then, we integrated short-range ordered mesopores into the walls of macropores to form a hierarchical pore structure. By incorporating graphene into this system, its electric conductivity can be enhanced. This is the first study to natively grow graphene on porous carbon. It is found that this material shows an excellent ORR performance with synergistically enhanced activities. Tafel analysis confirms that the good performance was brought from its unique structural advantages. (3) To further enhance the catalytic activity of the above materials with ideal hierarchical structures for ORR, we have introduced high active Fe-N species into the system during the fabrication. By delicate tuning of the Fe content, we are able to control the carbon nano-materials on the hierarchical porous carbon to form graphene or carbon nanotube. As a result, the catalyst has obtained a similarity high performance as Pt as a result of the successful combination of the desired merits for ORR on it. (4) Besides the optimization of materials structure, we have also doped graphene with both N and S, and studied the influence of dual dopants on its ORR activity. We found that a significant performance enhancement was achieved by dual-doping. From density function theory calculation, we found the synergistic effect was from the spin and charge densities redistribution brought by dual-doping of S and N, leading to a larger number of ORR active sites. The studies in this thesis have provided a thorough understand of the kinetic and mechanism of the ORR process on the Pt-free catalysts. The research has not only provided materials with optimized structure and high performance for ORR, but also showed an avenue on the materials' design and construction for further study.

Proton exchange membrane (PEM) fuel cells are promising clean energy converting devices with high efficiency and low to zero emissions. Such power sources can be used in transportation, stationary, portable and micro power applications. The key components of these fuel cells are catalysts and catalyst layers. “PEM Fuel Cell Electrocatalysts and Catalyst Layers” provides a comprehensive, in-depth survey of the field, presented by internationally renowned fuel cell scientists. The opening chapters introduce the fundamentals of electrochemical theory and fuel cell catalysis. Later chapters investigate the synthesis, characterization, and activity validation of PEM fuel cell catalysts. Further chapters describe in detail the integration of the electrocatalyst/catalyst layers into the fuel cell, and their performance validation. Researchers and engineers in the fuel cell industry will find this book a valuable resource, as will students of electrochemical engineering and catalyst synthesis.

This project was directed at reducing the dependence of PEM fuel cells catalysts on precious metals. The primary motivation was to reduce the cost of the fuel cell stack as well as the overall system cost without loss of performance or durability. Platinum is currently the catalyst of choice for both the anode & the cathode. However, the oxygen reduction reaction (ORR) which takes place on the cathode is an inherently slower reaction compared to the hydrogen oxidation reaction (HOR) which takes place on the anode. Therefore, more platinum is needed on the cathode than on the anode to achieve suitable fuel cell performance. As a result, developing a replacement for platinum on the cathode side will have a larger impact on overall stack cost. Thus, the specific objectives of the project, as stated in the solicitation, were to produce non-precious metal (NPM) cathode catalysts which reduce dependence on precious metals (especially Pt), perform as well as conventional precious metal catalysts currently in use in MEAs, cost 50% less compared to a target of 0.2 g Pt/peak kW, & demonstrate durability of greater than 2000 hours with less than 10% power degradation. During the term of the project, DOE refined its targets for NPM catalyst activity to encompass volumetric current density. The DOE Multi-Year RD & D Plan (2005) volumetric current density targets for 2010 & 2015 are greater than 130 A/cm3 & 300 A/cm3 at 800 mV (IR-free) respectively. The initial approach to achieve these targets was to use vacuum deposition techniques to deposit transition metal, carbon and nitrogen moieties onto 3M's nanostructured thin film (NSTF) catalyst support. While this approach yielded compounds with similar physicochemical characteristics as catalysts reported by others as active for ORR, the activity of these vacuum deposited catalysts was not satisfactory. In order to enhance catalytic activity additional process steps were introduced, the most successful of which was a thermal treatment. To withstand the high temperatures (~900 ðC), alternative supports to NSTF were introduced. A variety of carbon fabrics were tested for this purpose. Vacuum deposited materials were used as precursors & physicochemically transformed via thermal treatment to produce substantially better catalytic activity. This activity was further amplified by increasing the surface area of the carbon fabrics which lead to significant gains in fuel cell performance. The second synthetic approach is based on 3M nanotechnology & involves depositing precursor catalytic materials on high surface area supports, initially carbon. These materials were subsequently thermally treated in a nitrogen-containing gas atmosphere. While this approach is similar to others reported in the literature, we exploited 3M's nanotechnology platform & our expertise in the areas of synthesis & application of the precursor on the substrate. ORR activity proved higher for the materials produced via this approach. In fact, to our knowledge, the performance achieved on this effort exceeded the best previously reported for any NPM catalyst. With 4-nitroaniline as a precursor, the volumetric current density of our material achieved 19 A/cm3 at 800 mV, exceeding the value reported by DOE as the 2005 status (8 A/cm3) by a factor of more than two. We emphasize a unique feature of this project is that all measurements were done in real PEM fuel cells using 50-cm2 MEAs, therefore rendering credibility to the data for practical projection to a fuel cell stack application. In addition, with the price of the precursor nitroaniline only $1.5 kg on the commodity market enabling the DOE requirement of reducing the cost of the catalyst by a factor of two. A drawback of high-performing catalysts on carbon supports is their poor durability. Therefore, in the last stage of this project the focus of shifted toward improving the stability of the NPM catalyst. For that purpose alternative supports to carbon were introduced, The best catalyst synthesis methods remained practically the same for the new supports. Consequently, catalysts were made that were stable up to 1.4 V & one such material ran for over 1000 hours in a 50-cm2 fuel cell with no significant performance loss. In conclusion, by using precursor materials that are commodity items this project achieved the best performing & the most durable NPM catalyst reported thus far in PEM fuel cells. The knowledge base in the area of NPMC has been substantially increased & a solid platform for reaching the 2010 and 2015 targets of the DOE Multi-Year RD & D Plan has been established.