Controlled release of hydrogen isotope compounds and tunneling effect in the heterogeneously-catalyzed formic acid dehydrogenation

Abstract

The hydrogen isotope deuterium is widely used in the synthesis of isotopically-labeled compounds and in the fabrication of semiconductors and optical fibers. However, the facile production of deuterium gas (D2) and hydrogen deuteride (HD) in a controlled manner is a challenging task, and rational heterogeneously-catalyzed protocols are still lacking. Herein, we demonstrate the selective production of hydrogen isotope compounds from a combination of formic acid and D2O, through cooperative action by a PdAg nanocatalyst on a silica substrate whose surface is modified with amine groups. In this process, D2 is predominantly evolved by the assist of weakly basic amine moieties, while nanocatalyst particles in the vicinity of strongly basic amine groups promote the preferential formation of HD. Kinetic data and calculations based on semi-classically corrected transition state theory coupled with density functional theory suggest that quantum tunneling dominates the hydrogen/deuterium exchange reaction over the metallic PdAg surfaces.

Deuterium kinetic isotope effects as redox mechanistic criterions

“…81 The Arrhenius plots of the turnover frequencies in D 81 The H/D exchange reactions between formic acid and D 2 O were also found to involve a quantum tunneling effect, as evidenced by the large KIE value. 82 One of the largest KIE of 1380 at 232 K was reported for intramolecular 1,5-hydrogen atom transfer (1,5-HAT) in the decay of a the methoxy polyethylene glycol-substituted carbazyl (aminyl) radical in acetone (Figure 6, No. 13 in Table 1) in acetone.…”

Electrochemical CO2 reduction to high-concentration pure formic acid solutions in an all-solid-state reactor

“…800,000 metric tons of formic acid (HCOOH) is produced globally every year for a wide range of applications, including chemical production, cleaning, textile industry, and antiseptics 39 – 41 . More importantly, with the fast development of dehydrogenation catalysts 42 , formic acid now becomes an attractive hydrogen carrier due to its liquid phase under ambient conditions, high volumetric hydrogen density (53 g H 2 per liter of HCOOH), and low toxicity 43 – 45 . Producing this important energy carrier via electrochemical CO 2 RR will prevent net carbon emissions and make it a carbon neutral liquid fuel.…”

CO2 Electroreduction to Formate at a Partial Current Density up to 590 mA mg−1 via Micrometer‐Scale Lateral Structuring of Bismuth Nanosheets

“…[1][2][3][4] Formate is an important liquid product of CO 2 RR with a high product value per electron and has been widely applied in various energy and industrial fields, such as hydrogen storage and fuel cells. [5,6] Bi, Sn, and Pb have been demonstrated as formate-producing metals with high formate selectivity. [7][8][9][10][11] Among these catalysts, Bi is a potentially superior catalyst for industrial application since it is virtually nontoxic and relatively inexpensive.…”