Designing reliable and accurate isotope-tracer experiments for CO2 photoreduction.

The photoreduction of carbon dioxide (CO2) into renewable synthetic fuels is an attractive approach for generating alternative energy feedstocks that may compete with and eventually displace fossil fuels. However, it is challenging to accurately trace the products of CO2 photoreduction on account of the poor conversion efficiency of these reactions and the imperceptible introduced carbon contamination. Isotope-tracing experiments have been used to solve this problem, but they frequently yield false-positive results because of improper experimental execution and, in some cases, insufficient rigor. Thus, it is imperative that accurate and effective strategies for evaluating various potential products of CO2 photoreduction are developed for the field. Herein, we experimentally demonstrate that the contemporary approach toward isotope-tracing experiments in CO2 photoreduction is not necessarily rigorous. Several examples of where pitfalls and misunderstandings arise, consequently making isotope product traceability difficult, are demonstrated. Further, we develop and describe standard guidelines for isotope-tracing experiments in CO2 photoreduction reactions and then verify the procedure using some reported photoreduction systems.

Surface Reconstruction-Associated Partially Amorphized Bismuth Oxychloride for Boosted Photocatalytic Water Oxidation.

The molecule water activation is believed to be one of the most critical steps that is closely related to the proceeding of photoinduced reaction, such as overall water splitting, carbon dioxide conversion, and organic contaminant degradation. As metal oxides possessing a regular structure with high crystallinity are widely accepted as promising for effective catalysis, numerous studies have been devoted to the relevant photoinduced applications. However, their irregular derivative phases with lower crystallinity, which could exhibit tempting opportunities for catalytic activities, have long been ignored. Here, the surface-amorphized bismuth oxychloride is produced by homogeneous nanoparticle distribution through a rapid precipitation strategy. Comparing with its surface-crystallized counterpart, the partially amorphized bismuth oxychloride undergoes a fast surface reconstruction process under light irradiation, forming active surfaces with rich oxygen vacancies (OVs), leading to not only distinctive OV-mediated interfacial charge-transfer mechanisms with improved carrier dynamics but also robust water-surface interface with enhanced physical and chemical interaction, thus resulting in enhanced photocatalytic water oxidation. The strategy of optimizing by tuning the interfacial interaction behavior proposed in this work could broaden horizons for establishing more efficient partially amorphized energy conversion materials.