Active hydrogen species, including H atom (H·), hydride (H−), and proton (H+), play pivotal roles in a diverse array of significant reactions of hydrogenation, syngas conversion, and water electrolysis. Therefore, the detection and identification of active hydrogen species are essential to gain a deeper understanding of those catalytic processes. Despite earlier intensive research, the exact nature of active hydrogen species remains under intense dispute. In this study, we present a systematic investigation to probe active hydrogen species derived from H2 activation by the commercial platinum sponge and palladium powder using the electron paramagnetic resonance spin trapping technique. Our results reveal that the major reactive hydrogen species on the Pt surface is H+, and hence, the formation of H atom adducts with spin traps primarily follows the mechanism of proton coupled electron transfer, instead of H atom transfer. In contrast, for the Pd system, the dominant reactive hydrogen species behaves more like H atoms.
Zhang et al. (Wed,) studied this question.