According to an embodiment, a method for preparing a sea urchin-shaped zinc oxide (ZnO) nanowire comprises preparing a mixture of a ZnO nano-powder and a graphite powder and irradiating the mixture, in a container, with a microwave.

According to an embodiment, a method for preparing a sea urchin-shaped zinc oxide (ZnO) nanowire comprises preparing a mixture of a ZnO nano-powder and a graphite powder and irradiating the mixture, in a container, with a microwave.

Embodiments of the present disclosure provide for methods of hydrocarbon functionalization, methods and systems for converting a hydrocarbon into a compound including at least one group ((e.g., hydroxyl group) (e.g., methane to methanol)), functionalized hydrocarbons, and the like. Systems and methods as described herein can utilize photocatalysis.

A reaction chamber contains catalytic material(s). Tunable microwave source(s) each emit microwave radiation at corresponding time-varying microwave frequency(ies) or at simultaneous multiple different microwave frequencies. Microwave transmission element(s) irradiate the interior volume of the reaction chamber with the microwave radiation, emitted by the microwave source(s), that propagates along the transmission element(s) into the reaction chamber. The reaction chamber is characterized by a maximum temperature variation of a fixed-frequency, steady-state temperature spatial profile that results from irradiation of the reaction chamber by microwave radiation at a substantially fixed microwave frequency and at a reference microwave power level. Irradiation of the reaction chamber at the reference microwave power level by the microwave radiation with the time-varying microwave frequency(ies), or the simultaneous multiple different microwave frequencies, results in a multi-frequency temperature spatial profile having a maximum temperature variation less than the maximum temperature variation of the fixed-frequency, steady-state temperature spatial profile.

Embodiments of the present disclosure provide for methods of hydrocarbon functionalization, methods and systems for converting a hydrocarbon into a compound including at least one group ((e.g., hydroxyl group) (e.g., methane to methanol)), functionalized hydrocarbons, and the like. Systems and methods as described herein can utilize photocatalysis.

Provided is a method of producing graphene directly from a non-intercalated and non-oxidized graphitic material, comprising: (a) dispersing the graphitic material in a liquid solution to form a suspension, wherein the graphitic material has never been previously exposed to chemical intercalation or oxidation; and (b) subjecting the suspension to microwave or radio frequency irradiation with a frequency and an intensity for a length of time sufficient for producing graphene; wherein the liquid solution contains a metal salt dissolved in water, organic solvent, ionic liquid solvent, or a combination thereof. The method is fast (minutes as opposed to hours or days of conventional processes), environmentally benign, and highly scalable.

A process of forming an oxygen evolution catalyst includes the steps of: providing Co(NO.sub.3).sub.4; providing Na.sub.2WO.sub.4; combining the Co(NO.sub.3).sub.4 and Na.sub.2WO.sub.4 forming a solution; exposing the solution to a source of microwave energy and initiating a hydrothermal reaction forming hydrated CoWO.sub.4. The oxygen evolution catalyst including hydrated CoWO.sub.4 may be used to split water into oxygen and hydrogen ions.

A reaction chamber contains catalytic material(s). Tunable microwave source(s) each emit microwave radiation at corresponding time-varying microwave frequency(ies) or at simultaneous multiple different microwave frequencies. Microwave transmission element(s) irradiate the interior volume of the reaction chamber with the microwave radiation, emitted by the microwave source(s), that propagates along the transmission element(s) into the reaction chamber. The reaction chamber is characterized by a maximum temperature variation of a fixed-frequency, steady-state temperature spatial profile that results from irradiation of the reaction chamber by microwave radiation at a substantially fixed microwave frequency and at a reference microwave power level. Irradiation of the reaction chamber at the reference microwave power level by the microwave radiation with the time-varying microwave frequency(ies), or the simultaneous multiple different microwave frequencies, results in a multi-frequency temperature spatial profile having a maximum temperature variation less than the maximum temperature variation of the fixed-frequency, steady-state temperature spatial profile.