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The development of hydrogel electrolytes plays a critical role in high-performance flexible supercapacitor devices. Herein, a composite hydrogel electrolyte of polyacrylic acid (PAA) and graphene oxide (GO) has been successfully prepared, where the oxygen-containing functional groups of GO may crosslink and form hydrogen bonds with carboxyl on the molecular chain of PAA, thereby significantly enhancing the mechanical properties of a PAA-based gel electrolyte. The tensile strength increases from 4.0 MPa for pristine PAA gel to 6.1 MPa for PAA/GO composite gel, with the elongation at break rising from 1556% to 1950%. Meanwhile, GO promotes the transportation of electrolyte ions, which are favorable for enhancing the ionic conductivity of the PAA hydrogel. As a result, the assembled supercapacitor based on PAA/GO composite hydrogel electrolyte shows enhanced capacitance retention of 64.3% at a large current density of 20 A g−1 and excellent cycling stability over 10,000 cycles at 5 A g−1. Furthermore, the fabricated flexible supercapacitor devices could maintain outstanding electrochemical performance at various bending angles of 0–90°, indicating a promising prospect for the PAA/GO hydrogel electrolyte in flexible wearable fields. [ABSTRACT FROM AUTHOR]

• NiWO 4 induced partial oxidation of MXenes. • NiWO 4 /MXene heterojunction to construct photo-active biosensing platform. • EC-mechanism based PEC immuno-sensor for protein-specific antigen (PSA) biomarker. MXene-based hybrid composites are gaining substantial attention due to their impressive chemical and electronic characteristics. Herein, an in-situ engineered heterojunction is constructed using partially-oxidised Ti 3 C 2 T x sheets and photo-active NiWO 4 nanoparticles (NPs). The NiWO 4 NPs were used to induce partial surface oxidation of Ti 3 C 2 T x , resulting in the formation of a Ti 3 C 2 T x -TiO 2 /NiWO 4 hybrid composite (MX-NiWO 4). The electrocatalytic and photo-electrochemical (PEC) characteristics of MX-NiWO 4 were studied in reference to the reduced graphene oxide-NiWO 4 (rGO-NiWO 4) and H 2 O 2 -treated Ti 3 C 2 T x (MX-H 2 O 2) hybrids. The MX-NiWO 4 , based on its in-situ driven configuration, constructed an ideal interfacial arrangement for the electrocatalytic mechanism-based PEC immuno-sensing of prostate-specific antigens (PSA). The developed PEC biosensor was capable of detecting PSA, over a wide detection range of 1.2 fg.mL−1 to 0.18 mg.mL−1, with a detection limit of 0.15 fg.mL-1. The synergic integration of Ti 3 C 2 T x with photo-active NiWO 4 offers a superior signal response and practical applicability when used for the quantification of PSA from human saliva samples, anticipating the hybrid's promising future in clinical detection. [ABSTRACT FROM AUTHOR]

Procalcitonin (PCT) protein has recently been identified as a clinical marker for bacterial infections based on its better sepsis sensitivity. Thus, an increased level of PCT could be linked with disease diagnosis and therapeutics. In this study, we describe the construction of the photoelectrochemical (PEC) PCT immunosensing platform based on it situ grown photo-active CuWO4 nanospheres over reduced graphene oxide layers (CuWO4@rGO). The in situ growth strategy enabled the formation of small nanospheres (diameter of 200 nm), primarily composed of tiny self-assembled CuWO4 nanoparticles (2–5 nm). The synergic coupling of CuWO4 with rGO layers constructed an excellent photo-active heterojunction for photoelectrochemical (PEC) sensing. The platform was then considered for electrocatalytic (EC) mechanism-based detection of PCT, where inhibition of the photocatalytic oxidation signal of ascorbic acid (AA), subsequent to the antibody–antigen interaction, was recorded as the primary signal response. This inhibition detection approach enabled sensitive detection of PCT in a concentration range of 10 pg·mL−1 to 50 ng.mL−1 with signal sensitivity achievable up to 0.15 pg·mL−1. The proposed PEC hybrid (CuWO4@rGO) could further be engineered to detect other clinically important species. [ABSTRACT FROM AUTHOR]

Ceramic supported graphene oxide (GO)/Attapulgite (ATP) composite membrane (GOA) was simply prepared by vacuum filtration for efficient removal of heavy metal contamination. The ATP nanorods were incorporated within the laminar layers of GO, influencing the interlayer distance and facilitating greater number of channels for enhanced water transportation. The GOA possessed greater surface wettability with improved water flux rate of 6.3 L m−2 h−1 compared to 0.4 L m−2 h−1 measured for its pristine counter-part. The GOA demonstrated excellent rejection efficiency (nearly 100%) for heavy metal ions such as Cu2+, Ni2+, Pb2+ and Cd2+. The excellent separation efficiency of GOA could be ascribed to the synergic combination of size exclusion effect based on the formation of 3D network structures between the GO layers and increased electrostatic interaction in between the negatively charged surface moieties of GOA and heavy metal ions. More importantly, the use of Al 2 O 3 as a support substrate resulted in improved stability and allowed extended usage of the membrane for a period of 3500 min while maintaining 99% rejection efficiency for Cu2+ ions. The high flux rate, great water stability and prominent rejection capability of the designed membrane is suggestive of its practical application in removal of heavy metal contamination from water. Image 1 • Ceramic supported GO-ATP membrane was simply prepared by vacuum filtration. • Incorporation of ATP nanorods enhances the surface wettability and water flux. • Al 2 O 3 is an excellent substrate support that prolonged the stability of the GOA. • The GOA demonstrates excellent water stability with high flux rate. • The GOA exhibits excellent rejection of nearly 100% for heavy metal ions. [ABSTRACT FROM AUTHOR]