The
design and construction of efficient nanozymes are vital for
bio/chemo-sensing applications, while the systematic catalytic mechanism
study is the prerequisite. Tungsten oxide (WO3–x
) quantum dots (QDs), an alternative to conventional
heavy metal-containing semiconductor QDs, possess peroxidase-like
activity but limited catalytic efficiency. Therefore, the functions
of the typical oxygenous groups in determining the enzymatic activity
of the WO3–x
QDs by target-specifically
shielding the carboxyl (COOH), hydroxyl (OH), or carbonyl
(CO) groups, respectively, using a chemical titration
method. The results show that the CO groups could
accelerate the nanozymatic catalysis kinetically, while the OH
ones were the catalytically inhibitive sites, which were further corroborated
by the density functional theory (DFT) computations. The application
potential of the WO3–x
derivatives
with an enhanced catalytic ability was verified via the colorimetric
cholesterol sensing. The proposed method based on the benzoic anhydride
(BA)-modified WO3–x
QDs with deactivated
OH groups showed a wider linear range and higher sensitivity
than those based on the unmodified ones.