Solid-state supercapacitors can be fabricated by uniformly coating RuO ₂ onto vertical graphene (VG) using a simple, scalable, low-cost and solution-free method. The binder-free RuO ₂ /VG hybrid electrodes possess a high areal capacitance, low electrical resistance, good frequency response, and excellent stability, shedding light on the commercialisation of Ru-based energy storage devices.

Thermal chemical vapour deposition techniques for graphene fabrication, while promising, are thus far limited by resource-consuming and energy-intensive principles. In particular, purified gases and extensive vacuum processing are necessary for creating a highly controlled environment, isolated from ambient air, to enable the growth of graphene films. Here we exploit the ambient-air environment to enable the growth of graphene films, without the need for compressed gases. A renewable natural precursor, soybean oil, is transformed into continuous graphene films, composed of single-to-few layers, in a single step. The enabling parameters for controlled synthesis and tailored properties of the graphene film are discussed, and a mechanism for the ambient-air growth is proposed. Furthermore, the functionality of the graphene is demonstrated through direct utilization as an electrode to realize an effective electrochemical genosensor. Our method is applicable to other types of renewable precursors and may open a new avenue for low-cost synthesis of graphene films.

A green and efficient conversion of redundant biomass into functional nanomaterials holds the key to sustainable future technologies. Recently, vertical graphene nanosheets (VGS) have emerged as promising nanomaterials for integration in high-performance biosensors and supercapacitors, owing to their excellent and unique structural, morphological and electrical properties. However, when considering the conventional techniques utilized in nanofabrication, such as thermal or chemical routes, these often involve complex, eco-destructive and resource-consuming processes. Here we report on a single-step, potentially scalable, environmentally-benign and plasma-enabled method to synthesize VGS from an underutilized and natural by-product precursor, honeycomb. The VGS multifunctionality is highlighted by its integration as supercapacitor electrodes for energy storage, and as an electrochemical biosensor for the detection of the neurotoxic Amyloid-beta (Aβ) biomarker of Alzheimer's disease. The VGS were employed as binder-free supercapacitor electrodes, and demonstrated high specific capacitance up to 240 F g⁻¹ at a scan rate of 5 mV s⁻¹ and 100% capacitance retention after 2000 charge/discharge cycles. Furthermore, the VGS were functionalized with curcumin bioreceptors, and exhibited good sensitivity and selectivity towards the detection of neurotoxic Aβ species, and demonstrated a detection limit of 0.1 μg mL⁻¹.

Carbon nanostructures (CNs) are amongst the most promising biorecognition nanomaterials due to their unprecedented optical, electrical and structural properties. As such, CNs may be harnessed to tackle the detrimental public health and socio-economic adversities associated with neurodegenerative diseases (NDs). In particular, CNs may be tailored for a specific determination of biomarkers indicative of NDs. However, the realization of such a biosensor represents a significant technological challenge in the uniform fabrication of CNs with outstanding qualities in order to facilitate a highly-sensitive detection of biomarkers suspended in complex biological environments. Notably, the versatility of plasma-based techniques for the synthesis and surface modification of CNs may be embraced to optimize the biorecognition performance and capabilities. This review surveys the recent advances in CN-based biosensors, and highlights the benefits of plasma-processing techniques to enable, enhance, and tailor the performance and optimize the fabrication of CNs, towards the construction of biosensors with unparalleled performance for the early diagnosis of NDs, via a plethora of energy-efficient, environmentally-benign, and inexpensive approaches.