Covalently Interconnected Polymer Dot–WS₂ Nanosheet Heterostructure for Visible Light-Driven Hydrogen Production

Abstract

Photocatalytic hydrogen evolution is a promising solution to energy and environmental crises. The aim is to design an effective and strong photocatalyst that makes perfect use of solar energy. This is possible when catalysts have a good visible absorption ability, wide band gap, slow electron−hole pair recombination rate, and a large amount of active surface area. Considering the important properties of an excellent photocatalyst, in this work, by mixing variable amounts of chlorophyll-assisted exfoliated WS 2 nanosheets with the COOH and SH functional group polymer dots named P-dots-COOH and P-dots-SH, respectively, we have developed P-dots-COOH/WS 2 and P-dots-SH/WS 2 heterostructure composites. The P-dots-COOH/WS 2 80% heterostructure composite demonstrated a slightly higher current density (∼2.6 mA/cm 2 ) than the individual P-dots (∼1.8 mA/cm 2 ) and exfoliated WS 2 nanosheets (∼2.0 mA/cm 2 ). However, the P-dots-SH/WS 2 80% heterostructure composite demonstrated almost 200% (∼4.6 mA/cm 2 ) enhanced photocurrent density and low charge transfer resistance compared to P-dots-SH (∼2.0 mA/cm 2 ) and WS 2 nanosheet (∼2.0 mA/cm 2 ) materials. This was due to the coordination of the thiol functional group of Pdots-SH with the defect interface site of the chlorophyll-assisted exfoliated WS 2 nanosheets that reduced the charge transfer resistance, increased the number of electron−hole pairs, and reduced the electron−hole pair recombination rate. We discussed the possible photocatalytic hydrogen evolution mechanism in which the P-dots-SH valence band position was lower than the WS 2 valence band position. These results indicate that photogenerated electrons can be transferred from the conduction band of WS 2 to the conduction band of P-dots-SH, which reduces the possibility of recombination of electrons and holes and is more conducive to the transfer of electrons resulting in the hydrogen reduction potential, that is, the hydrogen production.

Semicrystalline Conjugated Polymers with Well‐Defined Active Sites for Nitrogen Fixation in a Seawater Electrolyte

“…[ 17,19,21,22,41–48 ] Additionally, the electrochemical surface areas (ECSAs) of LC‐PBDT‐TT, SC‐PBDT‐TT, and HC‐PBDT‐TT catalysts were determined by the double layer capacitances ( C dl ) in their corresponding cyclic voltammetric (CV) curves (Figure S19a–c, Supporting Information), which are 7.2, 6.2, and 5.4 mF cm −2 (Figure S19d, Supporting Information), respectively. [ 49,50 ] From the perspective of ESCAs, the SC‐PBDT‐TT catalyst also shows the highest NH 3 production rate (for additional discussion, see Supporting Information). Electrochemical impedance spectroscopy (EIS) analysis of SC‐PBDT‐TT was also conducted and shown in Figure S20, Supporting Information, indicating a low charge transfer resistance between the catalyst and electrolyte interface.…”

Co3O4 Nanosheet/g-C3N4 Hybrid Photocatalysts for Promoted H2 Evolution

“…The consumption of energy increases gradually with the development of technology. , It is necessary to find a green and renewable energy to relieve the growing demand of the nearly exhausted fossil energy . H 2 has a very extensive development potential in the new energy resource field for its environmental friendliness, wide resources, good thermal conductivity, high calorific value, light weight, convenience for transport, etc. , Since Fujishima and Honda developed photocatalytic water splitting using TiO 2 as a photocatalyst in 1972, photocatalytic H 2 evolution has become one of the most attractive methods in the field of green energy research. , …”

“…Co 3 O 4 is not appropriate to be used alone for H 2 evolution by water splitting because its conduction band potential is higher than the potential of the hydrogen reduction reaction. It is well known that constructing heterojunctions is an effective way for the improved photocatalytic performances. − g-C 3 N 4 is a good candidate for the heterojunction construction because of its suitable band energy level. − In this work, S-scheme heterojunction photocatalysts, Co 3 O 4 nanosheet/g-C 3 N 4 hybrids, were prepared by ultrasonic self-assembly combined with calcination and applied in photocatalytic water splitting for H 2 production. The effects of the g-C 3 N 4 content on the photocatalytic performances of Co 3 O 4 nanosheet/g-C 3 N 4 hybrids were studied.…”

In Situ Synergistic Ti2CTx/W18O49 Heterostructure for Photoelectrochemical Photodetector with Improved and Durable Photoresponse

“…This is because the former has three atomic layers per MXene Ti 2 CT x , whereas the latter has five or seven, resulting in a higher surface area with more active sites . MXenes have attracted a lot of interest in the past in the areas of photodetectors, sensors, shielding, and absorption of electromagnetic interference, catalysis, optical transmission, and modulation. , …”