Enhancing
the intrinsic activity of a benchmarked electrocatalyst
such as platinum (Pt) is highly intriguing from fundamental as well
as applied perspectives. In this work, hydrogen evolution reaction
(HER) activity of Pt electrodes, benchmarked HER catalysts, modified
with ultrathin sheets of hexagonal boron nitride (h-BN) is studied
in acidic medium (Pt/h-BN), and augmented HER performance, in terms
of the overpotential at a 10 mA cm–2 current density
(10 mV lower than that of Pt nanoparticles) and a lower Tafel slope
(29 ± 1 mV/decade), of the Pt/h-BN system is demonstrated. The
effects of h-BN surface modification of bulk Pt as well as Pt nanoparticles
are studied, and the origin of such an enhanced HER activity is probed
using density functional theory-based calculations. The HER charge
transfer resistance of h-BN-modified Pt is found to be drastically
reduced, and this enhances the charge transfer kinetics of the Pt/h-BN
system because of the synergistic interaction between h-BN and Pt.
An enormous reduction in the hydrogen adsorption energy on h-BN monolayers
is also found when they are placed over the Pt electrode [−2.51
eV (h-BN) to −0.25 eV (h-BN over Pt)]. Corrosion preventive
atomic layers such as h-BN-protected Pt electrodes that perform better
than Pt electrodes do open possibilities of benchmarked catalysts
by simple modification of a surface via atomic layers.
To counter the stress of a salt imbalance,
the cell often produces
low molecular weight osmolytes to resuscitate homeostasis. However,
how zwitterionic osmolytes would tune the electrostatic interactions
among charged biomacromolecular surfaces under salt stress has eluded
mainstream investigations. Here, via combination of molecular simulation
and experiment, we demonstrate that a set of zwitterionic osmolytes
is able to restore the electrostatic interaction between two negatively
charged surfaces that had been masked in the presence of salt. Interestingly,
the mechanisms of resurrecting charge interaction under excess salt
are revealed to be mutually divergent and osmolyte specific. In particular,
glycine is found to competitively desorb the salt ions from the surface
via its direct interaction with the surface. On the contrary, TMAO
and betaine counteract salt stress by retaining adsorbed cations but
partially neutralizing their charge density via ion-mediated interaction.
These access to alternative modes of osmolytic actions would provide
the cell the required flexibility in combating salt stress.
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