NiAl‐LDH In‐Situ Derived Ni₂P and ZnCdS Nanoparticles Ingeniously Constructed S‐Scheme Heterojunction for Photocatalytic Hydrogen Evolution

Abstract

Surface modification of photocatalytic materials is a good choice for improving semiconductor activity. Simple surface modification strategy and abundant active site construction are the key factors to improve photocatalytic activity. Take NiAl-LDH as the matrix, perform partial phosphating, and use the spatial confinement effect to generate highly dispersed Ni 2 P. Ni 2 P does not exist independently but on the 3D NiAl-LDH's surface. The introduction of NiAl-LDH-P can improve the utilization of Zn 0.5 Cd 0.5 S on solar energy and speed up the transfer rate of photogenerated carriers. Ni 2 P makes the active sites of phosphide more abundant, and the unique electron distribution of phosphide is conducive to photon capture, thus accelerating the hydrogen precipitation rate in the composite photocatalyst. Partial phosphating retains the 3D framework of hydrotalcite. The well-dispersed 0D to 3D S-scheme heterojunction hybrid material is composed of three-dimensional nano-flowers and tiny nano-particles alternately formed by countless nano-sheets. The multi-dimensional structured composite photocatalyst has abundant active sites, large specific surface area, and strong proton adsorption capacity, thus exhibiting more excellent photocatalytic hydrogen evolution performance. The maximum hydrogen production of the composite photocatalyst under 5 W LED simulated visible light for 5 h can reach 1982.43 μmol (39.64 mmol g À 1 h À 1 ) and the apparent quantum efficiency reached 6.22 % at 475 nm. The construction of the Zn 0.5 Cd 0.5 S/NiAl-LDH-P S-scheme heterojunction changes the hydrogen evolution site from Zn 0.5 Cd 0.5 S to Ni 2 P, so that the conduction band position of the composite photocatalyst becomes higher, the reduction ability is enhanced, and the hydrogen evolution The site changed from Zn 0.5 Cd 0.5 S to Ni 2 P, which is more conducive to the generation of hydrogen, thereby improving the activity and stability of hydrogen production. The space design of 0D and 3D provides new thinking for the design of the closely contacted S-scheme heterojunction photocatalytic. The application of surface modification strategies and the construction of abundant active sites point out the direction for further improving the composite photocatalytic activity.

Surface-Induced Engineering: P-Induced Formation of Surface Bonding States Based on the ZIF Synthesis Strategy for Photocatalytic Hydrogen Evolution

“…It can be seen from the figure that CoO–3NiO and 0.10P–CONO are both p-type semiconductors. It is well known that the valence band (VB) values of p-type semiconductors are 0.10 eV larger than the flat band potential tested under the calomel electrode. , That is, the VB values of CoO–3NiO and 0.10P–CONO are calculated to be 1.05 and 0.89 eV, respectively. Under the standard hydrogen electrode, the VB values of CoO–3NiO and 0.10P–CONO are calculated by E NHE = E SCE + 0.24 eV .…”

“…56,57 That is, the VB values of CoO−3NiO and 0.10P−CONO are calculated to be 1.05 and 0.89 eV, respectively. Under the standard hydrogen electrode, the VB values of CoO−3NiO and 0.10P−CONO are calculated by E NHE = E SCE + 0.24 eV 58.…”

Fabrication of NiFe‐PBA‐S / ZnCdS form S‐scheme for improved photocatalytic hydrogen evolution

“…Simultaneously, the lactic acid solution is oxidized by a large number of vacancies in the ZCS valence band 55‐57 . The built‐in electric field, energy band bending, and cullen gravity work together to keep photogenerated electrons and holes separated in the semiconductor with a high redox ability 58‐60 …”

“…[55][56][57] The built-in electric field, energy band bending, and cullen gravity work together to keep photogenerated electrons and holes separated in the semiconductor with a high redox ability. [58][59][60]…”

Surface-Induced Engineering: Formation of Induced Surface P(δ–)-Co/Ni(δ+)-O(δ–) Based on Nickel–Cobalt-Layered Double Hydroxide Nanoflowers for Photocatalytic Hydrogen Evolution

“…However, catalysts are mainly faced with the problem of high photogenerated carrier recombination rate in the process of photocatalysis. In order to solve this problem, many studies have suppressed the recombination of photogenerated electron holes by constructing a heterojunction at the catalyst interface, − doping technology, − and loaded single atom technology − to accelerate more photoproduction electrons to reduce H 2 O to generate hydrogen.…”