Design of High-Efficiency Visible-Light Photocatalysts for Water Splitting: MoS₂/AlN(GaN) Heterostructures

Abstract

Hydrogen fuel produced from water splitting using solar energy and a catalyst is a clean and renewable future energy source. Great efforts in searching for photocatalysts that are highly efficient, inexpensive, and capable of harvesting sunlight have been made for the last decade, which, however, have not yet been achieved in a single material system so far. Here, we predict that MoS2/AlN(GaN) van der Waals (vdW) heterostructures are sufficiently efficient photocatalysts for water splitting under visible-light irradiation based on ab initio calculations. Contrary to other investigated photocatalysts, MoS2/AlN(GaN) vdW heterostructures can separately produce hydrogen and oxygen at the opposite surfaces, where the photoexcited electrons transfer from AlN(GaN) to MoS2 during the photocatalysis process. Meanwhile, these vdW heterostructures exhibit significantly improved photocatalytic properties under visible-light irradiation by the calculated optical absorption spectra. Our findings pave a new way to facilitate the design of photocatalysts for water splitting.

Design of graphene-like gallium nitride and WS2/WSe2 nanocomposites for photocatalyst applications

“…Consequently, the valence band offset (VBO) between the GaN and WS2 (WSe2) is about 0.2 eV (0.1 eV for GaN/WSe2), whereas the conduction band offset (CBO) between them is about 1.1 eV (1.2 eV for GaN/WSe2). Based on the analysis and the DOSs presented above, the band edge potentials of the nanocomposites versus the normal hydrogen electrode (NHE) are depicted in Figs 3a and b [33,55,56]. The VBM energies of these two heterostructures are more positive than the oxidation potential (1.23 eV) of H2O/O2 for water splitting, and their CBM energies are more negative than the reduction potential for the reduction of H + to produce H2.…”

“…Recently, theoretical predications have confirmed that the single-layered graphene-like GaN possesses high thermal stability comparable to that of AlN monolayer which has been experimentally synthesized [30][31][32]. Subsequently the GaN monolayer was studied as the co-catalyst for MoS2 in consideration of the low catalytic efficiency of the pristine MoS2 [32,33]. The existence of the co-catalyst can effectively prevent the recombination of the photoinduced electrons and holes and eventually facilitate the charge separation.…”

Impact of N-plasma and Ga-irradiation on MoS2 layer in molecular beam epitaxy

“…With both methods, p-type doping was attained and was verified by softening and strengthening of characteristics phonon modes E The recent investigations reveal that the dissimilar heterojunctions formed by transition metal dichalcogenides (TMDs) and III-nitrides provide the route for novel devices in the area of optoelectronic, electronics, and water splitting applications. [1][2][3][4] In addition, 2D materials such as graphene, boron nitride nanosheets, and layered transition metal dichalcogenides (TMDs) were investigated as potential buffer layers for the epitaxial growth of III-V semiconductors on foreign substrates. [5][6][7][8] The use of TMDs, in particular, layered-MoS 2 as a buffer layer attracts the potential interest of researchers to address the issues such as large lattice and thermal expansion mismatch for the growth of GaN.…”

Electronic and optical properties of h-BN nanosheet: A first principles calculation

“…Among these structures, hexagonal nanostructures of group-III nitride semiconductors which are known as advanced materials have various technological applications in electro-magnetic and optoelectonic properties according to the atomic stoichiometry at their edges. High thermal conductivity, low compressibility and wide band gap properties make them interesting candidates for high-temperature diodes and electro-luminescent devices [7][8][9][10].…”