Photoelectrocatalytic degradation of wastewater and simultaneous hydrogen production on copper nanorod-supported coal-based N-carbon dot composite nanocatalysts

[Display omitted] •Coal as a raw material to prepare nitrogen-doped coal-based carbon dots (N-CDs).•Copper nanorod-supported N-carbon dot nanocatalysts were prepared by hydrothermal.•The anode degrades high CODCr wastewater, while the cathode produces clean energy.•The wastewater CODCr removal was 94.33% and the H2 yield was 272.0 mmol for 60 min.•The mechanism of photoelectrocatalytic degradation of wastewater were studied. Cotton pulp black liquor (CPBL) is a highly concentrated organic wastewater with complex composition, and its direct discharge is extremely harmful to the environment. As an important industrial raw material, hydrogen (H2) has a wide range of applications in many fields such as energy and chemicals. In the study, the composite catalyst N-CDs/Cu NRs was prepared in two steps: firstly, coal-based nitrogen-doped carbon dots (N-CDs) were prepared by the ammonia hydrothermal cutting method using Xinjiang Wucaiwan coal as the carbon source; secondly, N-CDs were loaded onto the surface of copper nanorods (Cu NRs; prepared by a liquid-phase reduction) by a hydrothermal method. While characterizing the structure of the material, the performance of photoelectrocatalytic (PEC) degradation of CPBL and H2 production using N-CDs/Cu NRs was investigated: this PEC double reaction takes place in an H-type photoreactor, where the anode degrades CPBL and the cathode produces H2. The chemical oxygen demand removal rate (RTCODCr) of CPBL reached 94.33% and the yield of H2 reached 272.0 mmol in 60 min of reaction. The GC–MS results showed that all aldehydes, phenols, acids, amines, ethers, and most alkanes, ketones and esters in CPBL could be degraded after 60 min.