Composites of Ag-Doped ZnIn₂S₄ Nanoplates with Graphitic Carbon Nitride and Reduced Graphene Oxide Nanosheets for Sunlight-Driven Hydrogen Production and Water Purification

Abstract

Photocatalysis is considered a promising technology to alleviate the energy crisis and environmental pollution; however, developing photocatalysts with improved light absorption efficiency is still a challenge. In this work, an effective strategy was proposed to synthesize a highly functional ternary nanocomposite (g-C 3 N 4 /RGO/AZIS) by coupling broader light-absorbing Ag-doped ZnIn 2 S 4 (AZIS) nanoplates with ultrathin g-C 3 N 4 and reduced graphene oxide (RGO) nanosheets. The 2D-on-2D stacking nanostructure of the composite provides a compact heterojunction, enlarged interfaces, and enriched active sites, resulting in the accelerated separation and relocation kinetics of charge carriers. Benefiting from these advantages, the g-C 3 N 4 /RGO/AZIS nanocomposite with systematically optimized contents of RGO and AZIS can serve as an efficient bifunctional photocatalyst for both H 2 production from water splitting and methyl orange (MO) photodegradation under the irradiation of visible light. The H 2 production rate of the ternary nanocomposite is 658.5 μmol h −1 g −1 , which is 38 times higher than that of plain g-C 3 N 4 . The operation mechanism is proposed based on the results of scavenger tests and photoelectrochemical analysis. The formation of a type-II heterostructure between AZIS nanoplates and g-C 3 N 4 nanosheets along with RGO with lower potential can maximize the separation efficiency of photogenerated electron−hole pairs and decrease the charge recombination. This work provides a viable strategy to develop bifunctional photocatalysts with enhanced performance for both H 2 production and degradation of organic dyes. KEYWORDS: photocatalysis, g-C 3 N 4 , reduced graphene oxide, nanocomposite, Ag-doped ZnIn 2 S 4

Ag-Doped ZnIn2S4 Nanosheets on Hollow Co9S8 Polyhedral Nanocages as Photocatalysts for Enhanced Hydrogen Production and Pollutant Reduction

“…A comparison of the hydrogen evolution rates between this work and previously reported similar systems under visible light is shown in Figure S3. The superior hydrogen evolution rate illustrates the great advantage of the hollow Co 9 S 8 /Ag:ZnIn 2 S 4 heterojunction over photocatalysts of similar types. − The photocatalytic hydrogen evolution reaction with an optimal ratio of the 1.0 wt % Co 9 S 8 /Ag:ZnIn 2 S 4 is evaluated through a long-term visible light cycle irradiation (Figure C). No significant deactivation was observed for 20 consecutive cycles, indicating the high stability of the prepared composite.…”

“…35 As shown in Figure 3B, according to the formula αhv = A(hv − E g ) n/2 and based on the direct transition (n = 1) of the Co 9 S 8 and the Ag:ZnIn 2 S 4 , the band gap values E g of (αhv) 2 for hv are 1.17 and 2.11 eV, respectively. 41 As described in Figure 3C,D The photocatalytic properties of the Co 9 S 8 , Ag:ZnIn 2 S 4, and Co 9 S 8 /Ag:ZnIn 2 S 4 composites under visible light were compared with data from the intuitive splitting water experiments. Due to the high-speed recombination of the photoinduced charge of Co 9 S 8 , its contribution to the photocatalytic hydrogen evolution is almost negligible.…”

“…In contrast, the advantageous hollow polyhedral nanocage structure of the Co 9 S 8 helps the Ag:ZnIn 2 S 4 expose more active sites and absorb more light to generate electron−hole pairs for redox reactions 35. As shown in Figure3B, according to the formula αhv = A(hv − E g ) n/2 and based on the direct transition (n = 1) of the Co 9 S 8 and the Ag:ZnIn 2 S 4 , the band gap values E g of (αhv)2 for hv are 1.17 and 2.11 eV, respectively 41. As described in Figure3C,D, the valence band (VB) position of the Co 9 S 8 and the Ag:ZnIn 2 S 4 are determined by VB XPS.…”

Enhanced photocatalytic hydrogen activities of CoV-LDH/ZnIn2S4 nanocomposites

“…[6][7][8] Since Lei et al first discovered in 2003 that the ZnIn 2 S 4 photocatalyst synthesized by a hydrothermal method has an excellent photocatalytic ability of water splitting to produce hydrogen under visible light, the majority of scientific researchers have turned their research attention toward ZnIn 2 S 4 -based photocatalysts. [9][10][11][12] As a typical transition chalcogenide semiconductor, ZnIn 2 S 4 is widely used in photocatalytic water splitting due to its unique crystal structure, suitable band gap and excellent visible light response. 13 However, due to the easy recombination of photogenerated electron and hole pairs, the carrier transfer efficiency is low and the photocatalytic activity is limited.…”

Composites of W18O49 Nanowires with g-C3N4/RGO Nanosheets for Broadband Light-Driven Photocatalytic Wastewater Purification

“…The third method involves the rational integration of other narrow-band gap semiconductors to construct heterogeneous photocatalysts that can more widely harvest sunlight. Moreover, the unique properties of each material can be combined to synergistically promote the transfer of the photogenerated charge carriers, making it the most advantageous approach. ,, …”