TiO2-HfN Radial Nano-Heterojunction: A Hot Carrier Photoanode for Sunlight-Driven Water-Splitting

Abstract

The lack of active, stable, earth-abundant, and visible-light absorbing materials to replace plasmonic noble metals is a critical obstacle for researchers in developing highly efficient and cost-effective photocatalytic systems. Herein, a core–shell nanotube catalyst was fabricated consisting of atomic layer deposited HfN shell and anodic TiO2 support layer with full-visible regime photoactivity for photoelectrochemical water splitting. The HfN active layer has two unique characteristics: (1) A large bandgap between optical and acoustic phonon modes and (2) No electronic bandgap, which allows a large population of long life-time hot carriers, which are used to enhance the photoelectrochemical performance. The photocurrent density (≈2.5 mA·cm−2 at 1 V vs. Ag/AgCl) obtained in this study under AM 1.5G 1 Sun illumination is unprecedented, as it is superior to most existing plasmonic noble metal-decorated catalysts and surprisingly indicates a photocurrent response that extends to 730 nm. The result demonstrates the far-reaching application potential of replacing active HER/HOR noble metals such as Au, Ag, Pt, Pd, etc. with low-cost plasmonic ceramics.

Transition Metal Nitrides Are Heating Up the Field of Plasmonics

“…The broad LSPR observed in metal nitrides can make them attractive materials to drive photochemical reactions using sunlight, but the rapid thermalization of excited electrons in plasmonic metal nitrides can make it difficult to effectively harvest hot electrons . Nevertheless, a handful of investigations have been led toward plasmon enhanced water-splitting, − CO 2 and HCO 3 – reduction, , and photocatalytic disinfection using plasmonic metal nitride nanostructures. In most studies, the nitrides are used as sensitizers to extend the absorption spectrum of a semiconductor (e.g., TiO 2 , CdS, In 2 O 3– x (OH) y ) into the visible and near-IR region.…”

In-Situ Monitoring the SERS Spectra of para-Aminothiophenol Adsorbed on Plasmon-Tunable Au@Ag Core–Shell Nanostars

“…The interaction between light and metals leads to the localized surface plasmon resonance (LSPR) effect on noble metallic nanostructures, including light scattering/absorbance [ 1 , 2 ], excitation of transient hot electrons and holes [ 3 , 4 ], plasmon-induced resonance energy transfer [ 5 , 6 ], near-field enhancement [ 7 ], as well as thermal effect [ 8 ]. The unique optical properties of metal nanostructures render them promising candidates in the areas of solar cells [ 9 , 10 ], imaging [ 11 , 12 ], photothermal therapy [ 13 , 14 ], seawater desalination [ 15 ], plasmon-driven photocatalysis [ 16 , 17 ], and surface-enhanced Raman scattering (SERS)-based signal amplification of trace molecules [ 18 , 19 ].…”