Catalyst-support interaction triggering biased electron flows between catalyst and reactant has been studied for electrocatalysis. The interaction was limited to the interfacial region between catalyst and support when nanoparticular catalysts,...

Abundant availability of seawater grants economic and resource‐rich benefits to water electrolysis technology requiring high‐purity water if undesired reactions such as chlorine evolution reaction (CER) competitive to oxygen evolution reaction (OER) are suppressed. Inspired by a conceptual computational work suggesting that OER is kinetically improved via a double activation within 7 Å‐gap nanochannels, RuO2 catalysts are realized to have nanoscopic channels at 7, 11, and 14 Å gap in average (dgap), and preferential activity improvement of OER over CER in seawater by using nanochanneled RuO2 is demonstrated. When the channels are developed to have 7 Å gap, the OER current is maximized with the overpotential required for triggering OER minimized. The gap value guaranteeing the highest OER activity is identical to the value expected from the computational work. The improved OER activity significantly increases the selectivity of OER over CER in seawater since the double activation by the 7 Å‐nanoconfined environments to allow an OER intermediate (*OOH) to be doubly anchored to Ru and O active sites does not work on the CER intermediate (*Cl). Successful operation of direct seawater electrolysis with improved hydrogen production is demonstrated by employing the 7 Å‐nanochanneled RuO2 as the OER electrocatalyst.

Electrocatalytic oxygen reduction reaction (ORR) in aqueous media proceeds along a pathway having multiple steps in which multiple surface intermediates are involved (* -> *OO -> *OOH -> *O -> *OH where * = active site of catalyst). Proton supplied from media plays a crucial role on the ORR mechanism. Therefore, pH of media affects the kinetics of ORR significantly. In the same vein, it is expected that the ORR activity is improved in the presence of proton donor (HD) around active sites of catalysts. In this presentation, we demonstrate a possibility that a series of proton donors are involved in protonation of the surface intermediates. The ORR overpotential was improved by 100 mV at pH 13 on transition metal oxide catalysts. The overpotential improvement was intensified as the pH of media decreased. It is suspected that the pH affects deprotonation of the proton donors (HD -> H+ + D-). High pH deprotonate the proton donors so that the effects of proton donors decrease. However, the proton of HD survives in acidic media so that the proton transfer from HD to active site is facilitated. The ORR overpotential gain was as large as 400 mV at pH 4 even if the oxide catalyst was not stable at the acidic pH. At pH 7, the overpotential improvement was estimated at 200 mV.