MOF-templated hollow Pd/CdS@Co3S4 nanocages with synergistic Z-scheme/Schottky effects for photoelectrochemical biosensing of chlorpyrifos featuring exceptional dynamic range

Conventional detection of organophosphorus pesticides (OPs) like chlorpyrifos (CPF) often faces challenges. This work presents a novel ternary synergistic PEC probe utilizing metal-organic framework (MOF)-templated Pd/CdS@Co ₃ S ₄ nanocages for sensing CPF. Derived from ZIF-67 via in situ sulfidation, the hollow nanocage architecture integrated CdS nanoparticles with Co ₃ S ₄ to form a direct Z-scheme heterojunction while decorating Pd quantum dots (QDs) created a Schottky barrier, implementing a crucial dual charge-transfer enhancement strategy. DFT simulations confirmed a 0.36 eV Fermi level difference at heterojunction interface, verifying a forced built-in electric field. The optimized Pd/CdS@Co ₃ S ₄ nanocomposite exhibited a remarkable ~ 5-fold photocurrent amplification over its pristine components, establishing a high-intensity signal baseline essential for accommodating wide-range concentration-dependent signal attenuation. Acetylcholinesterase (AChE)-immobilized biosensor quantified CPF via inhibition-triggered competitive electron consumption to attenuate photocurrent. The sensor demonstrated exceptional performance for CPF detection, most notably featuring a linear dynamic range spanning 4 orders of magnitude (0.1 ~ 2000 ng·mL ^− 1 ). Furthermore, it achieved a low detection limit (0.05 ng·mL ^− 1 , S/N = 3), outstanding specificity against interfering species, excellent long-term stability, and reliable accuracy in complex real samples (98.5 ~ 102.1%). This study proposes dual charge-transfer enhancement strategy and hollow architecture, addressing the broad-concentration-range in environmental pesticide detection with sensitivity and adaptability to real-world matrices.