Deciphering Z-scheme Charge Transfer Dynamics in Heterostructure NiFe-LDH/N-rGO/g-C3N4 Nanocomposite for Photocatalytic Pollutant Removal and Water Splitting Reactions

Abstract

A series of heterostructure NiFe LDH/N-rGO/g-C 3 N 4 nanocomposite were fabricated by combining calcinations-electrostatic self-assembly and hydrothermal steps. In this method, negatively charged N-rGO was electrostaticaly bonded to the self-assembled interface of n-n type g-C 3 N 4 /NiFe LDH hybrid. XRD and AFM results revealed successful formation of heterostructure nanocomposite due to the coupling effect of exfoliated NiFe LDH nanosheets with N-rGO and g-C 3 N 4 . Among the as synthesized heterostructure, CNNG3LDH performed superior photocatalytic activities towards 95 and 72% mineralization of RhB and phenol. Furthermore, CNNG3LDH could achieve the highest photocatalytic H 2 evolution rate of 2508 μmolg −1 2h −1 and O 2 evolution rate of 1280 μmolg −1 2h −1 under visible light irradiation. The CNNG3LDH possess lowest PL intensity, reduced arc of the Nyquist plot (43.8 Ώ) and highest photocurrent density (−0.97 mA cm −2 ) which revealed effective charge separation for superior photocatalytic activities. TRPL spectral results reveal the synergistic effect of layered component in CNNG3LDH for achievable higher life time of excitons of ~16.52 ns. In addition, N-rGO mediator based Z-scheme charge transfer mechanisms in CNNG3LDH were verified by the ESR and TA-PL studies. Enriched oxygen vacancy type defects in NiFe LDH and N-rGO mediated Z-scheme charge transfer mechanistic path strongly manifest the superior photocatalytic activities of the heterostructure materials.

Synthesis and photocatalytic H2‐production activity of plasma‐treated Ti3C2Tx MXene modified graphitic carbon nitride

“…As shown in Figure D, the samples possess similar decay curves. The lifetime of the carriers can be obtained by fitting the data based on double‐exponential function:where τ 1 and τ 2 present the PL lifetime; A 1 and A 2 are the corresponding amplitudes. The average value of lifetime of the samples can be calculated using the following equation:…”

Engineering Layered Double Hydroxide–Based Photocatalysts Toward Artificial Photosynthesis: State‐of‐the‐Art Progress and Prospects

“…Reproduced with permission. [ 152 ] Copyright 2019, Springer Nature. d) Diagram of the PEC water‐splitting mechanism on an integrating photoanode of BiVO 4 /rGO/NiFe‐LDH for water splitting.…”

“…Such a nanohybrid can be realized by the strong adhesion between the positively charged LDH sheets and the negatively charged N‐rGO sheets stemming from electrostatic interactions, resulting in the formation of NiFe‐LDH/N‐rGO/g‐C 3 N 4 (CNNG3LDH) for bolstered photocatalytic performance. [ 152 ] In another work by Ning et al, the rGO serves as the reduction cocatalyst in the TiO 2 /rGO/NiFe‐LDH nanoarray heterostructure system. [ 153 ] As such, the synergistic interaction and intimate interfacial interaction between the components pave a paradigm for advanced photocatalysts to facilitate enhanced charge separation, hence prolonging the lifetime of electron–hole pairs.…”

Advanced Exfoliation Strategies for Layered Double Hydroxides and Applications in Energy Conversion and Storage

“…However, this catalyst exhibited low H 2 generation rate due to the inactivity of ZnCr LDH for H 2 production. Nayak and Parida demonstrated the construction of heterostructure NiFe‐LDH/N‐rGO/g‐C 3 N 4 for photoinduced water splitting 59. The catalyst exhibited the photocatalytic H 2 evolution rate up to 2508 µmol g −1 2h −1 and O 2 evolution rate of 1280 µmol g −1 2h −1 .…”