Anchoring of Black Phosphorus Quantum Dots onto WO3 Nanowires to Boost Photocatalytic CO2 Conversion into Solar Fuels

Anchoring of BPQDs onto WO3 nanowires was constructed to successfully form a 0D–1D direct Z-scheme heterojunction, which was confirmed with Kelvin probe force microscopy studies, providing direct evidence for charge transfer and separation between BPQDs and WO3 in single nanowire. The BPQDs-WO3 heterojunction in the presence of water vapor displays excellent performance of photocatalytic reduction of CO2, exhibiting not only highly efficient carbon monoxide (CO) conversion, but also fortuitously significant amount of ethylene (C2H4), a highly value-added hydrocarbon species. The quantum efficiency was detected 0.79% with optimal loading amount of BPQDs. While precedent WO3-based Z-scheme photocatalyst systems never reported the formation of C2H4 from CO2, BPQD was demonstrated to play the critical role of the present photocatalytic transformation of C2H4. Both the armchair and zigzag edges of the BPQD proves favorable for the automatic coupling of two adsorbed *CO molecules into *CO-CO configuration, the major mechanism of the formation of C2H4. The onset potential of subsequent hydrogenation of *CO dimers for the formation of *CO-COH species on the BPQD is also calculated much lower than all the other catalysts that have been reported, and the onset potential of *CO-COH into *CO-CHOH is estimated even 30% lower than that on the Cu(100) surface which was recognized as the most effective catalyst for CO2 reduction into C2H4. Although the productivity of C2H4 is still low in the presence case, which can be improved through surface modification of applied BPQDs in our later work, this study proves the inspiring viability of BP-based heterostructures for production of highly value-added chemicals and advanced energy conversion and storage.