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The performance of soil microbial fuel cells (SMFCs) is greatly affected by the material of the anode. In this study, a low-cost material was fabricated based on rice husk charcoal (RHC) and cheaply available Bokuju (Japanese black drawing ink). Using the fabricated material to make the anode, the SMFC obtained a maximum power density of 9.52 μW/cm2. RHC showed a significant impact on the performance of the anode electrodes. Also, the ratio of RHC to Bokuju affected the output of the SMFC.

Photocatalyst is a material that can not only generate clean energy for the environment but can also be used in various applications such as antibacterial and antifouling properties. In this study, we compared the photocatalytic performance of titanium dioxide under indoor conditions by adjusting the amount of tin oxide attached to it. The amount of tin oxide deposited can be varied by adjusting the hydrothermal synthesis time. Appropriate tin oxide deposition recorded higher performance than excessive tin oxide deposition in both the yeast antimicrobial test and the water-splitting power generation test.

Mesoporous SiO2@TiO2 (MP-SiO2@TiO2) core-shell particles were fabricated using mesoporous SiO2 particles as a template in order to improve scattering performance and dye adsorption performance of the photoanode of dye-sensitized solar cells (DSSCs). They were used to make the scattering layer of the photoanode. Commercially available submicron TiO2 particles G1 that have the same particle size as the fabricated SiO2@TiO2 particles were also used to make the scattering layer to compare the photoelectric properties of the DSSC. The DSSC with the photoanode without a scattering layer generated a conversion efficiency of 1.54 %. By introducing a scattering layer composed of MP-SiO2@TiO2 to the photoanode, the conversion efficiency was improved to 2.82 %. In addition, the DSSC with the scattering layer composed of MP-SiO2@TiO2 generated higher conversion efficiency than that of the DSSC with the scattering layer composed of G1 (2.35 %). From these results, MP-SiO2@TiO2 particles produced a high performance as scatterers in the photoanode of DSSCs.

This study shows the effectiveness of titanium dioxide (TiO₂) on a floating microbial fuel cell (FMFC). In the experiment, when a UV cutoff filter attached halogen lamp was used, the power density of the FMFC using pristine TiO₂ (P25) and the FMFC using TiO₂ sintered at 650 °C were was 2.11mW/m2 and 10.44 mW/m2 respectively. Next, when measured without UV cutoff filter, pristine TiO₂ type FMFC and 650°C sintered TiO₂ type FMFC recorded 2.93 mW/m2 and 11.93 mW/m2 respectively. From this result, it was confirmed that the power density was improved up to five times when the UV cutoff filter was used and four times when it was not used. According to the results of X-ray Diffraction (XRD), 650°C sintered TiO₂ is composed of more rutile phase than pristine TiO₂.

Thin films made of carbon nanotubes are called buckypaper (BP), which is expected to be applied to electronic devices. Usually, BP is made by the chemical vapor deposition method. In this study, we used the vacuum filtration method to make low-cost BP. To justify the outstanding electronic performance of the fabricated BP, it was utilized to make the air-cathode of the aluminum-air battery. Since the BP is lighter and has a larger specific surface area than the carbon sheet, the aluminum-air battery can be miniaturized while increasing its performance. Furthermore, UV-ozone treatment was also applied to further improve the performance of the BP because it is able to clean and improve the surface conditions.

In this study, a portable and disposable paper-based microbial fuel cell (MFC) was fabricated. The MFC was powered by Rhodopseudomonas palustris bacteria (R. palustris). An activated carbon sheet-based anode pre-loaded organic matter (starch) and R. palustris was used. By using starch in the anode, R. palustris-loaded on the anode could be preserved for a long time in dry conditions. The MFC could generate electricity on-demand activated by adding water to the anode. The activated carbon sheet anode was treated by UV-ozone treatment to remove impurities and to improve its hydrophilicity before being loaded with R. palustris. The developed MFC could generate the maximum power density of 0.9 μW/cm2 and could be preserved for long-term usage with little performance degradation (10% after four weeks).

This study focused on investigating low-cost but high-performance catalyst materials used for the air cathode of the aluminum-air battery. Nickel, in the form of Ni(OH)2, was used as the catalyst because it is abundant and low-cost. The activated carbon sheet was used as the substrate to load the catalyst. The solvothermal synthesis method was used to synthesize the catalyst. The advantage of the solvothermal method is that the particle size can be reduced under high temperature and pressure conditions. The operation of some types of air-cathodes was examined. UV-ozone treatment of the air-cathode has also been investigated to enhance the performance of the battery.

Many efforts have been devoted to the improvement of metal-air batteries. Aluminum (Al) is the most abundant metal in the Earth’s crust and has high electrochemical potential. Therefore, the aluminum-air battery is one of the most attractive metal-air batteries. To overcome some disadvantages of the aluminum-air battery, some alloys of aluminum and several metals have been proposed. In this study, the performance improvement of the aluminum-air battery by doping zinc (Zn) to the aluminum anode was investigated. Zinc was doped to aluminum by a simple process. The difference in the characteristics of Zn-doped Al due to different heating temperature during the doping process was also investigated. The maximum power density of the battery was 2.5 mW/cm2.

Microbial fuel cells (MFCs) are a green technology that can directly convert electrical energy from chemical energy contained in organic wastewater. Rice is the most popularly consumed food in Asia. Rice washing before cooking produces an enormous amount of domestic sewage. Rice washing wastewater (RWW) contains various organic matters, minerals, and vitamins. Therefore, in this study, we utilized RWW as biofuel to operate a floating MFC (FMFC). The FMFC was designed with the air-cathode floating on the biofuel and the anode immersed in the biofuel. This design enables the device to float on wastewater sources and to harvest electricity directly from that source. Baker’s yeast and bacteria existing in a natural pond (natural bacteria) were used as biocatalysts. Experimental results showed that the FMFC could generate electricity from RWW using both the baker’s yeast and natural bacteria. The maximum power density ow the FMFC using the baker’s yeast was 1 mW/m2.

In this paper, a dye-sensitized solar cell based on organic MK2 dye, a quasi-solid electrolyte, and a flexible counter electrode was investigated. Two types of TiO2 nanoparticles with different sizes were used to make the photoanode with a bi-layer structure. The quasi-solid electrolyte was made based on polymethylmethacrylate (PMMA) and iodide/triiodide couple. The counter electrode was fabricated by electrophoresis deposition of carbon nanotube (CNT) mixed with diallyl dimethylammonium chloride (PDDA) on a flexible stainless-steel mesh. A cellulose separator was used to improve the stability of the solar cell. A simple and low-cost sealing method using polypropylene-based tape has been proposed and used for conducting the stability test. The maximum conversion efficiency of 2.5% (under simulated AM 1.5) was obtained with the fabricated quasi-solid dye-sensitized solar cells.

FliC-deficient Escherichia coli (E. coli) strain ( △ fliC) and its parent strain, wildtype K-12 (WT), were utilized to produce electricity in microbial fuel cells (MFCs). Although the two strains had similar growth curves, the biofilm of △ fliC generated a 193 % higher power density than that of WT. The biofilm formation test revealed that △ fliC was better than WT in biofilm formation on the anode in terms of bacterial cell concentration. This result provides valuable insight into the improvement of electricity production by E. coli-inoculated MFCs.

Water-activated paper-based batteries are expected to be low-cost disposable power sources for paper-based sensor applications. In this study, a disposable paper-based battery was developed. The battery used activated carbon powder loaded on a carbon sheet as the anode. The cathode was coated directly on a paper filter to fabricate an integrated proton exchange membrane cathode. Copper (II) chloride mixed with multiwalled carbon nanotube (CuCl2/CNT) was used as the cathode. Water was injected into the anode electrode to activate the battery. The maximum power density of 134. 6 μ W /cm2 was obtained with the anode loaded 17 mg cm−2 activated carbon powder. The power output of the battery is proportional to the amount of activated carbon loaded on the anode.

Titanium dioxide powder (TDP) and nickel-doped titanium dioxide powder (NiTDP) were synthesized by simple processes based on the sol–gel method. Nickel can be doped into titanium dioxide to narrow its energy bandgap; as a result, the visible-light photoactivity can be improved. In this study, the particle size of the fabricated TDP and NiTDP were larger than 100 nm, which is suitable for fabricating the light scattering layer (LSL) of the photoanode of dye-sensitized solar cells (DSSCs). The photoanode of our DSSCs comprised two layers: (1) a light absorbent layer made of commercial P25 titanium dioxide nanoparticles and (2) an LSL made of TDP or NiTDP. The DSSC used an organic MK-2 dye sensitizer, iodine-based redox electrolyte, and a multiwalled carbon nanotube counter electrode. Experimental results show that the photocurrent was significantly enhanced when the LSL was used. The DSSC with the absence of the LSL exhibited a conversion efficiency of 2.15%, while those of the DSSCs with the TDP-based LSL and NiTDP-based LSL were 2.37% and 2.78%, respectively. These results combined with UV–Vis spectra data, confirm the effectiveness of the extended visible-light photoactivity of the NiTDP-based LSL on the performance of the photoanode.

A novel, portable, and disposable paper-based microbial fuel cells (MFC) generating electricity from harmless strain of Escherichia coli (E. coli) has been developed. This MFC is on-demand electricity generation activated by a drop of tap water in a dry anode containing the biofilm of E. coli. A low-cost, simple-structure MFC case was created by a single layer of paper filter with high order of folding, which could support interchangeable dry bacteria-loaded anodes. The paper filter was innovatively engineered to make an integrated air-cathode proton exchange membrane (ACPEM) by coating carbon nanotube mixed with potassium ferricyanide on one surface and spraying hydrophobic solution on the other surface, respectively. The E. coli biofilm pre-inoculated in the anodes made of activated carbon sheet was simply dried in the air for the sake of long-term storage and usage. The dry anodes can be simply set in the MFC case with the readily prepared ACPEM, which can be used for on-demand power generation within seconds after adding water with maximum power density of 8.8μW/cm2.

Soil microbial fuel cells (SMFCs) are a promising cost-effective power source for on-demand electricity generation applications. So far, reported SMFC configurations are usually bulky and hard to setup. In this study, a low-cost portable plugged-type SMFC (PSMFC) was designed and fabricated for on-demand micropower generation. The PSMFC can be activated just by plugging into natural wet soil, which is easy to access in the natural condition. The PSMFC uses carbon-based electrodes for cost-effectiveness. After setting the PSMFC into the soil to activate, it started to produce electricity after 1 h and reached the power density of 7.3 mW/m2 after 48 h. The proposed PSMFC can potentially generate electricity for remote sensors or soil sensing systems.

Activated carbon has been popularly utilizing for countless applications such as purification of water, heavy metal removal, and natural gas and biogas storage. In this study, a novel phenomenon of activated carbon powder (ACP) has been utilized to realize a disposable water-activated battery. The battery is environmentally friendly because it is based on an ACP-loaded anode and a multiwalled carbon nanotube-coated air-cathode. The air-cathode was integrated on the backside of a paper-based proton exchange membrane. The battery case was made of cardboard for low cost and biodegradability. The proton exchange membrane was attached to the battery case. The anode was separately fabricated and could be simply set in the battery case for power generation. Because the air-cathode was used, the battery case could be reused for many cycles. The anode could also be reused for some cycles. Although the output power capacity of the battery is low in the range of mW kg−1 of ACP, it is made of low-cost and abundant materials, and therefore being able to be scaled up. The battery is a biodegradable on-demand micropower generation.

This study focuses on theoretically and experimentally enhancing the performance of a baker’s yeast-powered microbial fuel cell (MFC) by hybridizing the MFC and EFC (enzymatic fuel cells) technologies. To improve the power density of the MFC, commercially available alcohol and aldehyde dehydrogenase enzymes (ADHE) have been added to the anode chamber to oxidize ethanol, which is produced by Baker’s yeast (BKY) during the metabolic process, to acetic acid. This oxidation process contributes more power output for the MFC. BKY biofilm was formed in porous 3D activated carbon paper to make the anode. The combination of using the biofilm anode and ADHE for electricity generation by the MFC enabled about 19% improvement in the maximum power density if compared with the MFC without using ADHE. Also, aerobic and anaerobic culture conditions were investigated. The result showed that under the anaerobic culture condition, the MFC generated about 22% higher maximum power density than that of the aerobic condition. These results imply that the addition of ADHE can take full advantage of BKY-produced ethanol to boost overall BKY-powered MFC performance.

Titanium dioxide ( TiO 2 ) is the most popular photocatalytic material. However, its operation is limited to UV light only. In this paper, we tried to improve the visible light responsiveness of TiO2 by doping Nickel (Ni) using the sol-gel method. By combining Ni-doped TiO 2 powder with commercially available P25 TiO2 powder to make photocatalytic thin films, significant improvement in photocatalytic activity has been obtained. Furthermore, we also studied the relationship between the surface condition of photocatalytic thin films and their photocatalytic activity. The surface condition was improved by the multilayer electrophoresis deposition method. Based on experimental results, by combining 10 20 wt% Ni-doped TiO2 with P25 TiO2 , we could significantly enhance the photocatalytic activity of P25 TiO2 .

Microbial fuel cells (MFCs) have emerged as one of the promising technologies for energy-harvesting from domestic waste treatment. However, the slow cathodic reaction kinetics in MFCs causes a high overpotential of the oxygen reduction reaction (ORR) and leading to potential loss. Therefore, the development of effective cathode catalysts is required to facilitate the practical application of MFCs. Various studies have paid attention to improving the cathodic catalysis by developing various types of materials, which have properties such as active ORR catalytic activity, low-cost, durability, and scalability. In this chapter, the development status and fundamental principle of several catalysts used in the cathode of MFCs are discussed, which include electrocatalysts, photoelectrocatalysts, and biocatalysts.

Soil moisture and irrigation schedules generate impressionable agricultural productivity. In recent years, Soil Microbial Fuel Cell (SMFC) has been recently used as a sustainable technology because of its highly effective applications in power generation, environment pollution treatments, and sensing. Controlling the moisture of soil has a heavy impact on agricultural management. In this study, we set up a new design of SMFC for sensing soil water content. The SMFC is portable, compact, and easily installed. The SMFC operated at four states of soil moisture of 40%, 60%, 80%, and 100% soil water holding capacity (SWHC) was investigated in 25 days. The SMFC showed the highest humid sensitivity in the range from 60% to 80% SWHC. In the range of less than 60% SWHC, the soil moisture was not enough to activate and maintain the SMFC operation.

Several studies have been made on cell growth by the ultrasound irradiation. It is important to change the output, irradiation time and duty cycle for cell growth. The duty cycle determined the proportion of the time that the ultrasound was “on”. We can control cell growth by changing these three terms. The purpose of this study is to find the optimum conditions for cell growth and examine a new factor to influence cell growth. Cell concentration was determined by measuring the absorbance with a spectrophotometer. In this study, the absorbance became highest on 10min ultrasound irradiation and the duty cycle of 67% in experimental conditions. However, when 30 min ultrasound irradiation and the duty cycles of 86%, the absorbance became close to the highest value too. The results suggested that, in addition to the duty cycle, the off time of ultrasound might also affect the cell growth.