Photocatalytic hydrogen production from water splitting is of auspicious possibility to resolve the energy shortage and environmental anxieties. In the past decade, the combination of different carbon-based allotropes with semiconductors of different structure and unique properties to construct heterojunction, which can improve the charge separation, light absorption, and steadiness, offer a promising way to achieve efficient photocatalyst. This review aims to provide an overview of the development for the carbon nanomaterials (CNMs)-based photocatalysts used for hydrogen production from water splitting and photocatalytic degradation of organic pollutants in waste water. The recent progress of CNMs-based heterojunction, including various composite with graphene, fullerene, carbon quantum dots (CQDs), and carbon nanotubes (CNTs) were highlighted. Furthermore, a typical model of CNMs-based Z-scheme heterojunction was also addressed. Finally, a promising perspective on the future development of CNMs-based photocatalysts have been discussed.

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In this study, cellulose acetate and poly (4-methyl-1-pentene) (CA/PMP) nanofibers were co-electrospun with a blending ratio of 1:1 and followed by deacetylation treatment to produce cellulose/PMP nanofibers. The physical morphology of nanofibers was characterized by SEM which reveals even and bead-less morphology of nanofibers with an average diameter of 650 nm. FTIR study confirmed the removal of acetyl groups after deacetylation, and X-ray diffraction analysis was performed to analyze the crystalline nature of nanofibers. The calculated crystallinity and crystal size of CA/PMP nanofibers are 82 % and 34 Å. The tensile strength study revealed that the combination of both CA and PMP nanofibers with the blending ratio of 1:1 has improved the tensile strength of composite nanofibers. Further, the deacetylation process has also increased the tensile strength. The obtained tensile strength and Young’s modulus are 6.9 MPa and 195 MPa for cellulose/PMP nanofibers which could be a value addition in cellulose-based membranes.

Prior studies on heavy metal heterojunction with carbon nanomaterials for dye-sensitized solar cells (D-SSCs) found that they were not only toxic but also had poor stability and led to a difficult synthesis. In this work, nanomaterials with flexible nonwoven sheets were employed to improve cell efficiency and were easily synthesized with high stability, durability, washability, and flexibility. By incorporating carbon quantum dots (CQDs) into the anode and counter electrodes, it is possible to boost photon efficiency by scattering the sunlight and turning a huge amount into current density. Here in this research, Textile carbon–based flexible dye-sensitized solar cells (TC-DSSC) with N-doped CQDs may significantly increase solar cell efficiency. Carbon-based nanoparticles stacked with textile apparel (nonwoven bamboo) sheets enabled the desired flexible end applications to be achieved. The prepared material significantly increased solar cell efficiency to 11.26% compared to 8.04% of the one without CQDs. Carbon-based nanomaterials are stacked with textile apparel (nonwoven bamboo) sheets to make them lightweight, highly flexible, wearable, and user-friendly. Furthermore, compared to pure expanded graphite on the nonwoven substrate, a single electrode incorporating CQDs offered low impedance and high current/voltage. On the other hand, when tested for photocatalytic activity using spectrophotometry, the proposed counter electrode made of expanded graphite, PAN, and CQDs loaded on nonwoven material completely degraded the methylene blue dye in a very short period of time. The N-CQDs may prove to be very stable with outstanding washing endurance anchored with expanded graphite layered on a nonwoven medium with an optimum thickness.