Rational design of three-dimensional nickel borate/graphene nanoarrays for boosted photoconversion of anthropogenic CO2

Direct photoconversion of diluted CO 2 into solar fuels has theoretically and practically become a hot research topic. However, the low yields and poor selectivity of carbonaceous products hampered by the H 2 evolution reaction is still a challenge for its practical application. Herein, we demonstrate a three-dimensional (3D) nickel borate/graphene nanoarrays (Ni-B i /G) for diluted CO 2 photoreduction with boosted activity and selectivity. In simulated flue gas with 10% CO 2 , the pristine Ni-B i displays a low activity and low CO selectivity of 41.8%, indicating its tendency of producing H 2 in diluted CO 2 . However, after growing Ni-B i nanoarrays onto graphene nanosheets , the optimized 3D Ni-B i /G exhibits a high CO selectivity of 84.9% with a CO production rate of 5.1 μmol h −1 , which is about 2 times of the blank sample. The improved performance can be attributed to the synergistic effect of the introduction of rGO and unique 3D structure, which are conducive not only to accelerate the separation of photogenerated charges, but also to enrich active sites and enhance CO 2 adsorption. This work provides fundamental guidance to the rational design of well-designed hierarchical catalysts for photoconversion of low concentration CO 2 .