Anisotropic Au nanobypyramids with molybdenum disulfide for plasmon-enhanced electrocatalysis, biosensing and energy production.

The strategic integration of anisotropic plasmonic nanostructures with two-dimensional (2D) semiconductors presents an emerging route for designing multifunctional hybrid systems with advanced photoelectrochemical (PEC) capabilities. In this work, we report the synthesis of a core-shell nanohybrid, Au nanobipyramid@MoS2 (AuNBP@MoS2), wherein gold nanobipyramids are uniformly encapsulated by few-layer MoS2 nanosheets. This architecture promotes direct plasmon-semiconductor coupling under 808 nm near-infrared (NIR) excitation, enabling efficient hot electron generation, enhanced interfacial charge separation, and photothermal-assisted transport via localized surface plasmon resonance (LSPR). When immobilized on a glassy carbon electrode (AuNBP@MoS2/GC), the hybrid device delivers exceptional PEC performance for both nonenzymatic biosensing and electrocatalysis. The sensor exhibits ultrasensitive detection of H2O2 and glucose with wide linear ranges (10 μM-30 mM and 100 μM-8 mM), low detection limits (7.25 μM and 5.95 μM), and high sensitivities (376.86 and 23.42 μA mM-1 cm-2), accompanied by ∼11-fold photocurrent enhancement under LSPR. It further enables selective HeLa cancer cell detection via biomarker-triggered H2O2 release. In electrocatalysis, the hybrid electrode exhibits outstanding hydrogen evolution reaction (HER) activity, with a low onset potential (-0.18 V vs. RHE), an overpotential of -0.32 V at 10 mA cm-2, and a Tafel slope of 92 mV dec-1 under NIR illumination. Addition of ethanol as a sacrificial agent further reduces the overpotential to -0.316 V and enhances the exchange current density by ∼12-fold due to suppressed charge recombination and improved hot carrier utilization. Mechanistic investigations combining experimental and theoretical analyses attribute these enhancements to synergistic plasmonic effects, efficient hot electron injection, and photothermal contributions. This work underscores the immense potential of anisotropic plasmonic-semiconductor hybrids in driving next-generation technologies for biosensing, electrocatalysis, and sustainable energy applications.