Single Particle Hopping as an Indicator for Evaluating Electrocatalysts

Design and screening electrocatalysts for gas evolution reactions suffer from scanty understanding of multi-phase processes at the electrode-electrolyte interface. Due to the complexity of multi-phase interface, it is still a great challenge to capture gas evolution dynamics under operando condition to precisely portray the intrinsic catalytic performance of interface. Here, we establish a single particle imaging method to real time monitor a potential-dependent vertical motion or hopping of electrocatalysts induced by electrogenerated gas nanobubbles. The hopping feature of single particle is closely correlated with intrinsic activities of electrocatalysts, thus is developed to be an indicator to evaluate gas evolution performance of various electrocatalysts. This optical indicator diminishes interferences from heterogeneous morphologies, non-Faradaic processes and parasitic side reactions that are unavoidable in conventional electrochemical measurements, therefore enables precise evaluation and high-throughput screening of catalysts for gas evolution systems.

Process Characteristics of Water-based Self-curing Coatings for Sand Casting

The rheological and gas evolution characteristics of water-based self-curing coatings for sand casting were analyzed and the influence of coating-thickness and graded coating on self-curing rate of coatings was studied. It can be seen from the test results that: the new water-based self-curing coating has both the characteristics of thixotropic fluid and pseudoplastic fluid, which has moderate thixotropy rate and high brushing index, good brushability and excellent comprehensive balance of flow-levelling and anti-flowability. It can meet the rheological requirements of various coating methods. The self-curing speed of water-based self-curing coating increases in an approximately linear manner with the decrease of its thickness. Thick coating should be best to paint at one time in the premise of ensuring its surface quality. Although the gas evolution volume of the new water-based self-curing coating is approximately equal to that of ordinary water-based baking coatings, but the gas evolution speed of self-curing coatings is almost half as that of the latter, which provides good conditions for preventing gas hole defect of casting.