Jian Ku Shang

Even though the well-established Haber-Bosch process has been the major artificial way to "fertilize" the earth, its energy-intensive nature has been motivating people to learn from nitrogenase, which can fix atmospheric N2 to NH3 in vivo under mild conditions with its precisely arranged proteins. Here we demonstrate that efficient fixation of N2 to NH3 can proceed under room temperature and atmospheric pressure in water using visible light illuminated BiOBr nanosheets of oxygen vacancies in the absence of any organic scavengers and precious-metal cocatalysts. The designed catalytic oxygen vacancies of BiOBr nanosheets on the exposed {001} facets, with the availability of localized electrons for π-back-donation, have the ability to activate the adsorbed N2, which can thus be efficiently reduced to NH3 by the interfacial electrons transferred from the excited BiOBr nanosheets. This study might open up a new vista to fix atmospheric N2 to NH3 through the less energy-demanding photochemical process.

Incorporating carbon into Bi3O4Cl enhances its internal electric field by 126 times, which induces a bulk charge separation efficiency (ηbulk) of 80%. This ultrahigh ηbulk value presents a state-of-the-art result in tuning the bulk charge separation. The generated C-doped Bi3O4Cl has a noble-metal- and electron-scavenger-free water-oxidation ability under visible light, which is difficult to achieve with most existing photocatalysts. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Understanding the chemistry of hydrogen peroxide (H2O2) decomposition and hydroxyl radical (•OH) transformation on the surface molecular level is a great challenge for the application of heterogeneous Fenton system in the fields of chemistry, environmental, and life science. We report in this study a conceptual oxygen vacancy associated surface Fenton system without any metal ions leaching, exhibiting unprecedented surface chemistry based on the oxygen vacancy of electron-donor nature for heterolytic H2O2 dissociation. By controlling the delicate surface structure of catalyst, this novel Fenton system allows the facile tuning of •OH existing form for targeted catalytic reactions with controlled reactivity and selectivity. On the model catalyst of BiOCl, the generated •OH tend to diffuse away from the (001) surface for the selective oxidation of dissolved pollutants in solution, but prefer to stay on the (010) surface, reacting with strongly adsorbed pollutants with high priority. These findings will extend the scope of Fenton catalysts via surface engineering and consolidate the fundamental theories of Fenton reactions for wide environmental applications.

A central issue in understanding photocatalytic water splitting on a stoichiometric or defective nanostructured oxide surface is its adsorption mode and related reactivity. More than just improving the adsorption of water on oxide surfaces, we demonstrate in this work that surface oxygen vacancies (OVs) also offer a possibility of activating water toward thermodynamically enhanced photocatalytic water oxidation, while the water activation state, as reflected by its capability to trap holes, strongly depends on the structures of OVs. Utilizing well-ordered BiOCl single-crystalline surfaces, we reveal that dissociatively adsorbed water on the OV of the (010) surface exhibits higher tendency to be oxidized than the molecularly adsorbed water on the OV of the (001) surface. Analysis of the geometric atom arrangement shows that the OV of the BiOCl (010) surface can facilitate barrierless O–H bond breaking in the first proton removal reaction, which is sterically hindered on the OV of the BiOCl (001) surface, and also allow more localized electrons transfer from the OV to the dissociatively adsorbed water, leading to its higher water activation level for hole trapping. These findings highlight the indispensable role of crystalline surface structure on water oxidation and may open up avenues for the rational design of highly efficient photocatalysts via surface engineering.