A promising Ni/Co-doped Ta1O1.05 full-spectrum photocatalyst with significantly improved photocatalytic performance for rhodamine B degradation by introducing functional graphene quantum dots

Abstract

The limited visible and near-infrared light absorption capacity of tantalum oxide restricts its photocatalytic efficacy in organic pollutant photodegradation. Herein, we propose a strategy for synthesizing (Ta_0.9Ni_0.05Co_0.05)₁O_1.05 nanocubes modified with aspartic acid and tryptophan-functionalized and boron-doped graphene quantum dots (DWB-GQDs) via a one coordination-annealing approach. By complexing Ta(V), Ni(II), and Co(II) ions with DWB-GQD, followed by thermal pyrolysis at 800 °C in N₂, a hierarchically structured photocatalyst is achieved. The resultant material features a cube-like morphology enriched with oxygen vacancies and a graphene-modified surface. Strong coordination between DWB-GQD and metal ion ensures the uniform dispersion of Ta, Ni, and Co, while oxygen vacancies narrow the bandgap, extending light absorption to visible and near-infrared regions. The presence of graphene promotes the electron transfer kinetics and strengthens the interfacial affinity with polar electrolyte. The synergistic effects of Ni/Co dual doping and DWB-GQD integration yield an unprecedented photodegradation performance under solar irradiation. The optimized catalyst demonstrates 28.7-fold enhancement in rhodamine B degradation efficiency and a 108.3-fold increase in an apparent kinetic constant within 60 minutes compared with conventional counterparts. This study not only advances the rational design of high-performance photocatalysts for environmental remediation but also provides a universal platform for engineering metal oxide nanomaterials with tailored photoelectric properties for catalysis and sensing applications.