Cofunction of Protons as Dopant and Reactant Activate the Electrocatalytic Hydrogen Evolution in Emeraldine‐Polyguanine

Abstract

Functional conductive polymers represent an emerging class of nonmetallic electrocatalysts attractive to substitute scarce and expensive elements used today. Here the synthesis of emeraldine‐polyguanine as structural‐molecular analog to polyaniline is shown and the conducting biopolymer as molecular hydrogen electrocatalyst is applied. The polymerized and protonated nucleobase aids the catalytic electroreduction of protons over a peculiar mechanism, where, over amino‐association, protons coserve as dopant and reactant. In acidic media the electrocatalytic evolution of hydrogen at a Tafel slope of 79 mV dec−1 at 290 mV overpotential (10 mA cm−2) is reported. The 140h initial stability test demonstrates that the functionality of polymerized nucleobases can be harnessed for heterogeneous catalysis, i.e., as here demonstrated for the electroconversion of hydrogen.

Are Polyaniline and Polypyrrole Electrocatalysts for Oxygen (O2) Reduction to Hydrogen Peroxide (H2O2)?

“…50−52 PANI and PEDOT were also used as the polymer matrix for incorporated metal particles for the ORR as well as the electrochemical hydrogen evolution reaction (HER), 53,54 and recently, even pure PANI was described as an electrocatalyst itself for the HER. 55 The motivation for the present work has been the investigation of electropolymerized PANI and PPy films on GC and carbon paper (CP) electrodes, which are free of metal dopants. These two different carbon electrodes were chosen as models of flat and high-surface electrodes, respectively.…”

Electrochemical Hydrogen Storage in Amine‐Activated Polydopamine

“…Amines in conducting polydopamine were shown to steer electrocatalytic selectivity in different directions ( Figure ): Secondary amines, such as in the condensed indoline and indole‐fragments, implement hydrogen evolution reaction (HER). [ 46–48 ] Primary amines, such as present in the dopamine (‐DA‐) n building block, possessed too high binding energies so that they suppress the hydrogen evolution but therefore enable hydrogen electrosorption (HES).…”

“…We subsequently modified the structure of polydopamine toward mainly (‐DA‐) n monomers and by that achieved a polymer with mainly primary amines (‒NH 2 ) based on prior art synthesis. [ 44–46,48,49 ] We reduced the reaction temperature of the oxidative chemical vapor deposition (oCVD) polymerization to 150 °C and achieved a polymer with 70% primary amines. This amine‐activated polydopamine (aaPDA) showed effective HES similar to palladium with a maximum of the hydrogen capacity close to −0.2 V versus RHE.…”

Long‐Lasting Electrospun Co3O4 Nanofibers for Electrocatalytic Oxygen Evolution Reaction

“…[2] Particularly, hydrogen gas is recognized as a clean energy carrier, when obtained through CO 2 -neutral technologies. [3] Nonetheless, the oxygen evolution reaction (OER) is the complementary half-reaction of the hydrogen evolution reaction (HER), being of outmost interest not only for HER but also for carbon dioxide reduction reaction and metal air batteries. [4] To increase the reaction rate, to lower the overpotential (η) and to stabilize the operation conditions for the abovementioned processes many suitable electrocatalysts have been researched towards OER.…”

“…Realizing this reaction is industrially getting more and more important in order to supply the present‐day civilization with sustainable energy since a trend about energy‐related crises combined with environmental pollution is ascending . Particularly, hydrogen gas is recognized as a clean energy carrier, when obtained through CO 2 ‐neutral technologies . Nonetheless, the oxygen evolution reaction (OER) is the complementary half‐reaction of the hydrogen evolution reaction (HER), being of outmost interest not only for HER but also for carbon dioxide reduction reaction and metal air batteries .…”