Synthesis of Metal Alloy Nanomaterials with Unconventional Crystal Phases for Fuel Cell Electrocatalysis

Description

Fuel cells represent a promising class of energy conversion devices in view of their superior energy efficiency, environmental friendliness, and negligible carbon emissions. Electrochemical processes occurring at the cathode and anode of fuel cells enable the direct transmission of chemical energy into electricity. Currently employed monometallic noble metal catalysts in fuel cell reactions, mainly Pt and Pd, often fail to satisfy the requirements for large-scale commercial applications, where catalysts should simultaneously exhibit superior activity, high stability, and low cost. To address this challenge, alloying Pt and Pd with earth-abundant non-noble metals allows for reducing the loading of noble metals. Moreover, the synergistic effect among various components offers the potential for better electrochemical performance than all of their monometallic counterparts. So far, tremendous efforts have been made to regulating the morphology, composition, and size effect of metal alloy nanomaterials to achieve enhanced performances. Phase engineering of nanomaterials (PEN) has recently emerged as another intriguing way for modulating the functions and enhancing the catalytic performance of metal nanomaterials by tuning their atomic arrangements. Apart from the conventional thermodynamically stable crystal structures, metal nanomaterials featuring unconventional crystal phases show distinct properties and demonstrate considerable potential for various applications. Impressively, these unconventional crystal phases possess unique atomic arrangements, featuring electric structures and/or coordination environments that differ from the conventional phases, which confer superior catalytic performance in comparison to the thermodynamically stable counterparts. However, it is still a challenge to controllably synthesize metal alloy nanomaterials with desirable atomic arrangement by wet-chemical methods due to the thermodynamically unstable nature of some unconventional crystal phases. Notably, our recent work has demonstrated that metal alloy nanomaterials with unconventional crystal phase,e.g., 2H-phase PdCu alloy nanoparticles could show excellent electrocatalytic performances in electrocatalytic reactions, especially fuel cell electrocatalysis,e.g., oxygen reduction reactions (ORR), outperforming their conventional counterparts, which motivates us to further develop efficient methods for preparing more metal alloy nanomaterials with unconventional crystal phase. In this proposal, we aim to develop general and robust synthetic approaches toward the controllable preparation of metal alloy nanomaterials with unconventional crystal phases including bimetallic/multi-metallic nanoalloys, and heterostructured nanoalloys. Moreover, we will study their formation mechanism, and investigate their properties and structure-performance relationship in fuel cell electrocatalysis.