University of Waterloo

About: University of Waterloo is a education organization based out in Waterloo, Ontario, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 36093 authors who have published 93906 publications receiving 2948139 citations. The organization is also known as: UW & uwaterloo.

The application of graphene and its composites in oxygen reduction electrocatalysis: a perspective and review of recent progress

Abstract: The pressing necessity of a sustainable energy economy renders electrochemical energy conversion technologies, such as polymer electrolyte fuel cells or metal–air batteries, of paramount importance. The implementation of these technologies at scale still faces cost and operational durability challenges that stem from the conventionally used oxygen reduction reaction (ORR) electrocatalysts. While years of progress in ORR catalyst research has yielded some very attractive material designs, further advances are still required. Graphene entered the picture over 10 years ago, and scientists have only recently achieved a level of understanding regarding how its specific properties can be fine-tuned for electrocatalyst applications. This paper provides a critical review of the knowledge generated and progress realized over these past years for the development of graphene-based ORR catalysts. The first section discusses the application potential of graphene or modified graphene as platinum nanoparticle catalyst supports. The second section discusses the important role that graphene has played in the development of non-precious metal ORR catalysts, and more particularly its role in pyrolyzed transition metal–nitrogen–carbon complexes or as a support for inorganic nanoparticles. Finally the development of heteroatom doped graphene species is discussed, as this has been demonstrated as an excellent method to fine-tune the physicochemical properties and induce catalytic activity. Throughout this paper, clear differentiation is made between acidic and alkaline ORR catalysts, and some common misconceptions or improper testing practices used throughout the literature are revealed. Synthesis strategies and how they pertain to the resulting structure and electrochemical performance of graphene are discussed. In light of the large body of work done in this area, specific strategies are suggested for perpetuating the advancement of graphene-based ORR electrocatalysts. With concerted efforts it is one day likely that graphene-based catalysts will be a staple of electrochemical energy systems.

Contextual constraints on prototype generation and their multilevel consequences for leadership perceptions

Abstract: It has become increasingly evident that no single prototype or style of leadership applies to all situations. In fact, we argue that definitions of leadership depend upon innumerable situational and contextual factors related both to the leader being perceived and to the broader external environment. To date, however, there is no theoretical framework that easily explains how perceivers integrate such a broad range of factors. In the current paper, we first present a model, based on recent advances in cognitive science, that allows for the simultaneous cognitive integration of multiple factors influencing the definition of leadership. We contend that this model can be used to understand both the stability and flexibility that is witnessed in the application of leadership prototypes. The framework is then integrated with the idea of alternative levels of analysis, providing a new perspective on how levels of analysis issues can be explored. Finally, we discuss the practical implications of our framework.

The Light: Nutrient Ratio in Lakes: The Balance of Energy and Materials Affects Ecosystem Structure and Process

Abstract: The amounts of solar energy and materials are two of the chief factors determining ecosystem structure and process. Here, we examine the relative balance of light and phosphorus in a set of freshwater pelagic ecosystems. We calculated a ratio of light: phosphorus by putting mixed‐layer mean light in the numerator and total P concentration in the denominator. This light: phosphorus ratio was a good predictor of the C:P ratio of particulate matter (seston), with a positive correlation demonstrated between these two ratios. We argue that the balance between light and nutrients controls “nutrient use efficiency” at the base of the food web in lakes. Thus, when light energy is high relative to nutrient availability, the base of the food web is carbon rich and phosphorus poor. In the opposite case, where light is relatively less available compared to nutrients, the base of the food web is relatively P rich. The significance of this relationship lies in the fact that the composition of sestonic material...