Electricity Generation and Pollutant Degradation Using a Novel Biocathode Coupled Photoelectrochemical Cell

Abstract

The photoelectrochemical cell (PEC) is a promising tool for the degradation of organic pollutants and simultaneous electricity recovery, however, current cathode catalysts suffer from high costs and short service lives. Herein, we present a novel biocathode coupled PEC (Bio-PEC) integrating the advantages of photocatalytic anode and biocathode. Electrochemical anodized TiO2 nanotube arrays fabricated on Ti substrate were used as Bio-PEC anodes. Field-emission scanning electron microscope images revealed that the well-aligned TiO2 nanotubes had inner diameters of 60-100 nm and wall-thicknesses of about 5 nm. Linear sweep voltammetry presented the pronounced photocurrent output (325 μA/cm(2)) under xenon illumination, compared with that under dark conditions. Comparing studies were carried out between the Bio-PEC and PECs with Pt/C cathodes. The results showed that the performance of Pt/C cathodes was closely related with the structure and Pt/C loading amounts of cathodes, while the Bio-PEC achieved similar methyl orange (MO) decoloration rate (0.0120 min(-1)) and maximum power density (211.32 mW/m(2)) to the brush cathode PEC with 50 mg Pt/C loading (Brush-PEC, 50 mg). The fill factors of Bio-PEC and Brush-PEC (50 mg) were 39.87% and 43.06%, respectively. The charge transfer resistance of biocathode was 13.10 Ω, larger than the brush cathode with 50 mg Pt/C (10.68 Ω), but smaller than the brush cathode with 35 mg Pt/C (18.35 Ω), indicating the comparable catalytic activity with Pt/C catalyst. The biocathode was more dependent on the nutrient diffusion, such as nitrogen and inorganic carbon, thus resulting in relatively higher diffusion resistance compared to the brush cathode with 50 mg Pt/C loading that yielded similar MO removal and power output. Considering the performance and cost of PEC system, the biocathode was a promising alternative for the Pt/C catalyst.

Designing Photoelectrodes for Photocatalytic Fuel Cells and Elucidating the Effects of Organic Substrates

“…[12] This is am uch higher powero utput than that typically reported for microbial fuel cells (< 0.1 mW cm À2 ). [13,14] To date, the studies of photoanode materials for PFCs have been largely limited to TiO 2 , [15][16][17] whereas the selectiono fo rganic substrates hasa lso been confined to several compounds,s uch as methanol, glucose, and dyes. [18] In this work, we explore the design of PFCs with ar ange of photoanodes, namely TiO 2 ,WO 3 ,and Nb 2 O 5 ,preparedb ya nodization.…”

Highly Efficient and Visible Light Responsive Heterojunction Composites as Dual Photoelectrodes for Photocatalytic Fuel Cell

“…To overcome the above mentioned drawbacks, the studies on either developing visible light responsive photoanodes [11][12][13][14] or replacing Pt by p-type semiconductor as the photocathode [15,16] become equally important, leading to the development of dual photoelectrodes for PFC system. However, so far, these PFCs have been identified with its shortcomings that the photoactivity and photostability of the electrodes are poor, which limits their application.…”

The effect of different exposed facets on the photoelectrocatalytic degradation of o-chlorophenol using p-type Cu 2 O crystals

“…As a promising technology, photoelectrocatalytic degradation has attracted increasing attention for its ability to efficiently decompose refractory organic pollutants that cannot be eliminated biologically, due to its convenience, environmental compatibility, cost-effectiveness, versatility and safety [1][2][3][4][5][6][7]. Photoelectrocatalysis, as an enhanced photocatalytic technique, holds great promise for effective wastewater purification by decreasing the recombination of photogenerated electron-hole pairs via applying a bias potential.…”

“…Thus, the degradation efficiency of organic contaminants could be improved, and the toxic and refractory intermediates generated during electrochemical oxidation could be decomposed by photocatalysis-induced radicals. However, in conventional photoelectrocatalytic degradation, most of the studies have focused on the improvement of photocatalysts [1,8] or anodic electrode materials [2][3][4][5]7,9], while few studies have paid attention to cathodic electrode materials that also substantially influence both reaction selectivity and efficiency [6]. The reason is that some critical challenges still remain in the application of active cathodes for photoelectrocatalytic water treatment, including the low efficiency of photo-electric conversion under natural sunlight, short service life, high cost, secondary contamination, etc.…”