Intrinsic Properties of Macroscopically Tuned Gallium Nitride Single‐Crystalline Facets for Electrocatalytic Hydrogen Evolution

Abstract

The anisotropy of crystalline materials results in different physicala nd chemical properties on different facets, which warrants an in-depth investigation.M acroscopically facet-tuned,h igh-purity gallium nitride( GaN) single crystalsw ere synthesised and machined,a nd the electrocatalytic hydrogen evolution reaction( HER) wasu sed as the model reaction to show the differences among the facets. DFT calculations revealed that the Ga and Ns ites of GaN (100) had ac onsiderably smaller DG H* value than those of the metal Ga site of GaN (001) or Ns ite of GaN (00À1), therebyi ndicating that GaN (100) should be more catalyti-cally activef or the HER on accounto fi ts nonpolar facet. Subsequente xperiments testified that the electrocatalytic performance of GaN (100) was considerablym ore efficient than that of other facets for both acidic and alkalineH ERs. Moreover,t he GaN crystal with ap referentially (100) active facet had an excellently durable alkaline electrocatalytic HER for more than 10 days. This work provides fundamentali nsightsi nto the exploration of the intrinsic propertieso fm aterialsa nd designing advanced materials for physicochemical applications.

High‐Quality GaN Crystal Grown on Laser Decomposed GaN–Sapphire Substrate and Its Application in Photodetector

“…The stress of LDMGA prepared with different laser energies was analyzed by Raman spectroscopy test on the surface and the interior. [ 32 ] The E 2 (high) phonon mode peak position can reveal the internal stress clearly. The E 2 (high) phonon peak position was used to estimate the stress by the following equation [ 33 ] where the σ was the stress and the Δ ω was the E 2 (high) peak shift compared to the stress‐free GaN.…”

Growth of Freestanding Gallium Nitride (GaN) Through Polyporous Interlayer Formed Directly During Successive Hydride Vapor Phase Epitaxy (HVPE) Process

“…Sample 4 was grown with three steps covering all proportions. The stress of GaN grown by HVPE was analyzed by Raman spectroscopy, tested on the surface [28]. The E 2 (high) phonon mode peak position can reveal the internal stress clearly.…”

Metal nitride-based nanostructures for electrochemical and photocatalytic hydrogen production

“…Gallium nitride with different crystal orientations has been engaged in HER application [ 243 , 244 ]. However, the scarcity of Ga and high cost makes gallium-based nitrides make them less attractive for commercialization.…”

“…The Tafel slope of 85 mV dec −1 is achieved, which is much lower when compared to that of nonporous Pt decorated GaN (105 mV/dec) [ 243 ]. In another interesting study, Hu et al studied the effect of anisotropy of three different single-crystal GaN facet materials with an overpotential of 168 mV, 234 mV and 205 mV for GaN(100,), GaN(001) and GaN(00–1), respectively, recorded at 10 mA cm −2 where the higher catalytic activity of GaN(100) is attributed to the low adsorption-free energy of H* (ΔG H* ) calculated from DFT measurements [ 244 ]. Moreover, the GaN (100) material performed better in acidic media (36 mV/dec, 10 days) with much better stability when compared to alkaline solution (45 mV/dec, 5000 cycles).…”