Ni12P5 nanoparticles embedded into porous g-C3N4 nanosheets as a noble-metal-free hetero-structure photocatalyst for efficient H2 production under visible light

Abstract

Transition metal phosphides (TMPs) have recently been thrust into the limelight as promising substitutes for precious noble metal-based cocatalysts for photocatalytic H₂ evolution. Herein, colloidally synthesized Ni₁₂P₅ nanoparticles were successfully embedded into porous g-C₃N₄ nanosheets through a facile solution-phase approach under sonication. The as-prepared photocatalysts with an optimum 5 wt% anchoring of Ni₁₂P₅ (5NP-CN) displayed an excellent H₂ production activity of 535.7 μmol g⁻¹ h⁻¹ under visible light irradiation. The high apparent quantum yield (AQY) of 4.67% at 420 nm was achieved in the 5NP-CN system for the production of H₂, exceeding a large scientific spectrum of literature studies on the TMP-based catalysts. The superior photocatalytic H₂ evolution of Ni₁₂P₅/g-C₃N₄ was predominantly attributed to the formation of intimate contact interfaces, in which Ni₁₂P₅ nanoparticles with high purity and good crystallinity were homogeneously embedded into the porous g-C₃N₄ nanosheets, thus facilitating the separation and transfer of photogenerated charge carriers. Meanwhile, a possible photocatalytic mechanism of Ni₁₂P₅/g-C₃N₄ hybrid nanocomposites was proposed and corroborated by photoluminescence (PL) spectroscopy and photoelectrochemical (PEC) results. As such, the present reported synthetic route to the g-C₃N₄-based photocatalysts incorporating Ni₁₂P₅ paves a new way for the advancement of g-C₃N₄ and a cornucopia of colloidal nanocrystals, which will be auspicious toward the nanoarchitecture engineering of noble-metal-free heterojunction interfaces for application in renewable energy production.