Unusual Ligand Assistance in Molecular Electrocatalysis via Interfacial Proton Charge Assembly

Abstract

We show that the ability of the ligand to reorganize the electric double layer (EDL) often dominates the electrocatalysis contrary to their inductive effect in the spectrochemical series, leading to counterintuitive electrocatalysis. With water oxidation and chlorine evolution as the probe reactions, the same catalytic entity with carboxy functionalized ligand exhibited surprisingly higher electrochemical activity in comparison to the aggressively electron-withdrawing nitro functionalized ligands, which is contrary to their actual location in the spectrochemical series. Spectroscopic and electrochemical analyses suggest the enrichment of catalytically active species in the carboxy substituted ligand via proton charge assembly in the EDL that in turn enhances the kinetics of the overall electrochemical process. This demonstration of less obvious ligands becoming indispensable in electrocatalysis suggests a blind designing of ligands solely based on their inductive effect should be reconsidered as it will prevent the utilization of the maximum potential of the molecule in electrocatalysis.

Electrochemical energy storage in an organic supercapacitor via a non-electrochemical proton charge assembly

“…We recently explored how a proton charge assembly can modulate the electrocatalytic behavior of Co-based phthalocyanines via the modulation of the surface charge of the molecules. 29 We anticipated that this type of proton charge assembly on the molecule should increase the local density of anions residing in the electric double layer, which in turn should ensure that these molecules are a suitable platform for charge storage applications. Specifically, in this work, we show how ligand functionalization combined with non-redox active units such as –COOH/NH 2 results in the metal phthalocyanine molecule becoming a potential platform for supercapacitive charge storage with enhanced energy and power capability.…”

Tuning a palladium(ii) phthalocyanine embedded hybrid electrocatalyst for the hydrogen evolution reaction

“…The extended aromaticity and conjugation provided by nitro (–NO 2 ) groups to the palladium complex make Pd( ii )TNPc more stable compared to parent Pc. 35,36…”

Fuel from waste: electrosynthesizing ammonia directly from agricultural digestate through ligand isomerization

“…1a) to bring out the ligand assistance in electrocatalysis unambiguously. 46–48 Several characterizations were performed to validate the synthesis of the molecules. Matrix-Assisted Laser Desorption Ionisation-Time of flight (MALDI-TOF) furnished the mass of molecular ion peak at 571, 631 and 631, which corresponds to NiPc, α-TANiPc and β-TANiPc respectively, in Fig.…”