  Additive manufacturing, called 3D printing, starts to play an unprecedented
role in developing many applications in industrial or personalized products.
The conductive composite structures require additional treatment to achieve an
electroactive surface useful for electrochemical devices. In this paper, the
surfaces of carbon black/poly(lactic acid) CB-PLA printouts were activated by
electrolysis or enzymatic digestion with proteinase K, or a simultaneous
combination of both. Proposed modification protocols allowed for tailoring
electrochemically active surface area and electron transfer kinetics determined
by electrochemical techniques (CV, EIS) with [Fe(CN)6]4-/3- redox probe. The
X-ray photon spectroscopy and SEM imaging were applied to determine the
delivered surface chemistry. The CB-PLA hydrolysis in alkaline conditions and
under anodic polarization greatly impacts the charge transfer kinetics. The
enzymatic hydrolysis of PLA with proteinase K has led to highly efficient
results yet requiring an unsatisfactory prolonged activation duration of 72 h,
efficiently reduced by the electrolysis carried out in the presence of the
enzyme. Our studies hint that the activation protocol originates from surface
electropolymerization rather than synergistic interaction between electrolysis
and enzymatic hydrolysis. The detailed mechanism of CB-PLA hydrolysis supported
by electrolysis has been elaborated since it pawed a new route towards a
time-efficient and environmentally-friendly activation procedure.
