▎ 摘　　要

NOVELTY - Preparing a carbon material involves mechanically treating plant leaves to obtain plant leaf extracts, and filtering the extracts many times to finally obtain clear and transparent plant extracts, which are refrigerated for later use. The solid plant extract and nitrogen source are weighed, dissolved in dimethyl sulfoxide, and stirred to obtain a clear solution. The obtained clear solution is heated to 160-200°C, kept for 8-15 hours, and cooled to room temperature to obtain sulfur-nitrogen co-doped graphene quantum dot (S,N-GQDs) carbon nanomaterials. USE - Method for preparing carbon material for formaldehyde purification, i.e., for adsorbing and photocatalytically degrading formaldehyde (claimed). ADVANTAGE - The method enables to prepare carbon material using cheap raw materials, simple synthesis method and wide application prospect. The method is performed under mild reaction conditions, is cost effective, and is suitable for batch production. The powder form of S,N-GQDs has higher adsorption performance and higher adsorption capacity to formaldehyde. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a carbon material.