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In this work, the typical honeycomb-nanoparticle heterostructure with honeycomb TiO 2 nanotube arrays (HTNTs) as light harvesting unit and Bi 2 MoO 6 nanoparticles (BMO) as recognition unit was prepared for highly sensitive and selective nano-enzymatic photoelectrochemical L-cysteine biosensor. [Display omitted] • The typical honeycomb-nanoparticle heterostructure between HTNTs and BMO improves the light harvesting behavior and the separation efficiency of the electron-hole pairs. • BMO nanoparticles fully dispersed on HTNTs with large specific surface area provides more sites for Cyst recognition. • Cyst can be specifically recognized through the Bi-S bonds. • The PEC enzyme-free biosensor shows good performance for Cyst with low detection limit and wide linear range. Improving light harvesting behavior and recognition sites of sensor is an effective way to achieve highly sensitive and selective detection of nano-enzymatic photoelectrochemical (PEC) L-cysteine (Cyst). In this work, the Bi 2 MoO 6 -TiO 2 composite (BMO-HTNTs) with honeycomb TiO 2 nanotube arrays (HTNTs) as light harvesting unit and Bi 2 MoO 6 nanoparticles (BMO) as recognition unit was prepared. The typical honeycomb-nanoparticle heterostructure between HTNTs and BMO improves the separation efficiency of the electron-hole pairs. Moreover, BMO nanoparticles fully dispersed on HTNTs with large specific surface area provide more sites for Cyst recognition. The composite exhibited the enhanced light absorption and higher photocurrent density at 0.2 V (vs. Ag/AgCl), which was 4 times than that of HTNTs under simulated light. Ingeniously, Cyst can not only be specifically recognized through the Bi-S bonds but also act as electron donor to scavenge the photogenerated holes of BMO-HTNTs, resulting in the increase of PEC responses. The PEC sensor showed superior analytical performance for Cyst detection with two linear regression equations in the range of 500 nM to 500 μM and a detection limit of 150 nM. The results of the enzyme-free sensor on practical urine and serum samples demonstrated its promising application in biological monitoring. [ABSTRACT FROM AUTHOR]