The ability to meet higher effluent quality requirements and the reduction of energy consumption are the biggest challenges in wastewater treatment worldwide. A large proportion of the energy generated during wastewater treatment processes is neglected and lost in traditional wastewater treatment plants. As a type of energy harvesting system, triboelectric nanogenerators (TENGs) can extensively harvest the microscale energies generated from wastewater treatment procedures and auxiliary devices. This harvested energy can be utilized to improve the removal efficiency of pollutants through photo/electric catalysis, which has considerable potential application value in wastewater treatment plants. This paper gives an overall review of the generated potential energies (e.g., water wave energy, wind energy, and acoustic energy) that can be harvested at various stages of the wastewater treatment process and introduces the application of TENG devices for the collection of these neglected energies during wastewater treatment. Furthermore, the mechanisms and catalytic performances of TENGs coupled with photo/electric catalysis (e.g., electrocatalysis, photoelectric catalysis) are discussed to realize higher pollutant removal efficiencies and lower energy consumption. Then, a thorough, detailed investigation of TENG devices, electrode materials, and their coupled applications is summarized. Finally, the intimate coupling of self-powered photoelectric catalysis and biodegradation is proposed to further improve removal efficiencies in wastewater treatment. This concept is conducive to improving knowledge about the underlying mechanisms and extending applications of TENGs in wastewater treatment to better solve the problems of energy demand in the future.

Improving Wastewater Treatment by Triboelectric-Photo/Electric Coupling Effect.

Bio-based materials with special wettability for oil-water separation

CO2 capture and conversion has been prospected as an auspicious technology to simultaneously tackle the rise in global CO2 emission and produce value-added fuels with the goal of accomplishing carbon neutrality. A sustainable route to achieve this is via the utilization of solar energy, thereby harnessing the abundant and nonexhaustive resource to shift our reliance away from rapidly depleting fossil fuels. Graphitic carbon nitride (g-C3N4) and its allotrope have earned its rank as a fascinating metal-free photocatalyst due to its superior stability, high surface-area-to-volume ratio, and tunable surface engineering. By leveraging these properties, robust carbon nitride-based nanostructures are engineered for photocatalytic CO2 conversion to energy-rich C1C2 product, which is indispensable in the chemical industry. Thus, this review presents the latest panorama of experimental and computational research on tuning the local electronic, surface chemical coordination environment, charge dynamics and optical properties of low-dimensional carbon nitride and its allotropes toward highly selective and efficient CO2 photoconversion. To name a few, structural engineering, point-defect engineering, heterojunction construction, and cocatalyst loading. To advance this frontier, critical insights are elucidated to establish the structure-performance relationship and unravel primary factors dictating the selectivity of C1C2 molecules from CO2 reduction. External-field assisted photocatalysis such as with electric (photoelectro-) and heat (photothermal) is discussed to uncover the synergistic contributions that drive the development in photochemistry. Last, future challenges and prospects are outlined for the potential application of solar-driven CO2 conversion, along with the scale-up strategy from the economic viewpoint toward the rational development of high-efficiency carbon nitride catalysts. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/inf2.12279

Solar‐powered chemistry: Engineering low‐dimensional carbon nitride‐based nanostructures for selective
 
 CO
 2
 
 conversion to
 
 C
 1
 C
 2
 
 products

Advanced oxidation process: a sustainable technology for treating refractory organic compounds present in industrial wastewater

Triboelectric nanogenerator enhanced radical generation in a photoelectric catalysis system via pulsed direct-current

Fundamentals and applications of photoelectrocatalysis as an efficient process to remove pollutants from water: A review.

The electrophoretic deposition of titanium dioxide (TiO2) nanoparticles (Degussa P25) onto a boron-doped diamond (BDD) substrate was carried out to produce a photoanode (TiO2/BDD) to apply in the degradation and mineralization of sodium diclofenac (DCF-Na) in an aqueous medium using photoelectrocatalysis (PEC). This study was divided into three stages: i) photoanode production through electrophoretic deposition using three suspensions (1.25%, 2.5%, 5.0% w/v) of TiO2 nanoparticles, applying 4.8 V for 15 and 20 s; ii) characterization of the TiO2/BDD photoanode using scanning electron microscopy and cyclic voltammetry response with the [Fe(CN)6]3-/4- redox system; iii) degradation of DCF-Na (25 mg L-1) through electrochemical oxidation (EO) on BDD and PEC on TiO2/BDD under dark and UVC-light conditions. The degradation of DCF-Na was evaluated using high-performance liquid chromatography and UV-Vis spectroscopy, and its mineralization measured using total organic carbon and chemical oxygen demand. The results showed that after 2 h, DCF-Na degradation and mineralization reached 98.5% and 80.1%, respectively, through PEC on the TiO2/BDD photoanode at 2.2 mA cm-2 under UVC illumination, while through EO on BDD applying 4.4 mA cm-2, degradation and mineralization reached 85.6% and 76.1%, respectively. This difference occurred because of the optimal electrophoretic formation of a TiO2 film with a 9.17 μm thickness on the BDD (2.5% w/v TiO2, time 15 s, 4.8 V), which improved the electrocatalysis and oxidative capacity of the TiO2/BDD photoanode. Additionally, PEC showed a lower specific energy consumption (1.55 kWh m-3). Thus, the use of nanostructured TiO2 films deposited on BDD is an innovative photoanode alternative for the photoelectrocatalytic degradation of DCF-Na, which substantially improves the degradation capacity of bare BDD. 

Carol Sigcha-Pallo

Papers

Fundamentals and applications of photoelectrocatalysis as an efficient process to remove pollutants from water: A review.

Photoelectrocatalytic degradation of diclofenac with a boron-doped diamond electrode modified with titanium dioxide as a photoanode.