The present work suggested the use of waste oil palm frond as an alternative precursor for nitrogen-doped carbon quantum dots (NCQDs) and proposed a straightforward

in-situ

hydrothermal method for the preparation of NCQDs/TiO

2

nanocomposites. The elemental composition

morphological

structural and optical characteristics of NCQDs/TiO

2

nanocomposites have been comprehensively investigated. The successful grafting of NCQDs on TiO

2

matrix was confirmed by the formation of TiOC bond and the electronic coupling between the π-states of NCQDs and the conduction band of TiO

2

. For the first time

the oil palm frond-derived NCQDs/TiO

2

was adopted in the photodegradation of methylene blue (MB) under visible-light irradiation. As a result

the photocatalytic efficiency of NCQDs/TiO

2

nanocomposites (86.16%) was 2.85 times higher than its counterpart TiO

2

(30.18%). The enhanced performance of nanocomposites was attributed to the pivotal roles of NCQDs serving as electron mediator and visible-light harvester. Besides

the optimal NCQDs loading was determined at 4 ml

while the removal efficiency of NCQDs/TiO

2

-4 was the highest at a catalyst dosage of 1 g·L

-1

under alkaline condition. This research work is important as it proposed a new insight to the preparation of biomass-based NCQDs/TiO

2

using a facile synthetic method

which offers a green and sustainable water remediation technology.