Charge Modulation in Graphitic Carbon Nitride as a Switchable Approach to High‐Capacity Hydrogen Storage

Abstract

Electrical charging of graphitic carbon nitride nanosheets (g-C4 N3 and g-C3 N4 ) is proposed as a strategy for high-capacity and electrocatalytically switchable hydrogen storage. Using first-principle calculations, we found that the adsorption energy of H2 molecules on graphitic carbon nitride nanosheets is dramatically enhanced by injecting extra electrons into the adsorbent. At full hydrogen coverage, the negatively charged graphitic carbon nitride achieves storage capacities up to 6-7 wt %. In contrast to other hydrogen storage approaches, the storage/release occurs spontaneously once extra electrons are introduced or removed, and these processes can be simply controlled by switching on/off the charging voltage. Therefore, this approach promises both facile reversibility and tunable kinetics without the need of specific catalysts. Importantly, g-C4 N3 has good electrical conductivity and high electron mobility, which can be a very good candidate for electron injection/release. These predictions may prove to be instrumental in searching for a new class of high-capacity hydrogen storage materials.

Materials design for electrocatalytic carbon capture

“…% at full loading. 42 Despite the promising possibilities demonstrated in the calculations, the present issues confronting efforts to experimentally verify the findings with these materials are that g-C 4 N 3 is not yet readily synthesized in useful quantities, while g-C 3 N 4 is a semiconductor with bandgap calculated to be just under 2 eV, meaning that it will not display good conductivity as needed for the charging process.…”

“…This can be immensely frustrating for all sorts of reasons, but every so often a powerful new discovery reinforces one's confidence that the effort is worth it in spades! In this contribution, following a preliminary body of work, 18,22,25,26,36,37,41,42,48 we have taken a step back to consider some underlying trends that dictate electrocatalytic CO 2 binding in a group of 1:1 X-N graphene analogue materials. The results indicated that the electro-responsive switching behavior correlates with a change in the preferred CO 2 binding site from N to the adjacent X atom as more negative charge is introduced into the system.…”

Charge-controlled switchable H2 storage on conductive borophene nanosheet

“…However, the electric field strength in this study is around 23000 MVm -1 , which was too large for experimental realization. On the other hand, researchers also found that when extra charges were injected into adsorbents, the gas adsorption capacity of this adsorbents could be extremely enhanced [17][18][19][20][21]. Notably, the kinetics of gas adsorption and release could be modulated by tuning charge density, yielding a controlled adsorption and desorption process.…”

“…Notably, the kinetics of gas adsorption and release could be modulated by tuning charge density, yielding a controlled adsorption and desorption process. Until now, various materials have been developed and explored for charge-controlled H2 storage [17][18][19][20][21]. B-doped graphene has been proposed as an excellent charge-modulated H2 storage material.…”

First-Principle Framework for Total Charging Energies in Electrocatalytic Materials and Charge-Responsive Molecular Binding at Gas–Surface Interfaces

“…Charging of electrocatalytic materials can be an efficient method for modifying or modulating molecular interactions and reactivity at heterogeneous interfaces, including gas capture and separation processes and electrochemical and electrocatalytic reactions. − Heterogeneous charge-responsive molecular binding to electrocatalytic materials has been predicted in several recent works. For instance, density functional theory (DFT) calculations have revealed that gas phase CO 2 molecules undergo weak physisorption (through van der Waals interactions) on hexagonal boron nitride ( h -BN) in the absence of charging.…”