Nitrobenzene (NB) is a toxic compound that is often found as a pollutant in the environment. The present removal strategies suffer from high cost or slow conversion rate. Here, we investigated the conversion of NB to aniline (AN), a less toxic endproduct that can easily be mineralized, using a fed-batch bioelectrochemical system with microbially catalyzed cathode. When a voltage of 0.5 V was applied in the presence of glucose, 88.2 ± 0.60% of the supplied NB (0.5 mM) was transformed to AN within 24 h, which was 10.25 and 2.90 times higher than an abiotic cathode and open circuit controlled experiment, respectively. AN was the only product detected during bioelectrochemical reduction of NB (maximum efficiency 98.70 ± 0.87%), whereas in abiotic conditions nitrosobenzene was observed as intermediate of NB reduction to AN (decreased efficiency to 73.75 ± 3.2%). When glucose was replaced by NaHCO(3), the rate of NB degradation decreased about 10%, selective transformation of NB to AN was still achieved (98.93 ± 0.77%). Upon autoclaving the cathode electrode, nitrosobenzene was formed as an intermediate, leading to a decreased AN formation efficiency of 71.6%. Cyclic voltammetry highlighted higher peak currents as well as decreased overpotentials for NB reduction at the biocathode. 16S rRNA based analysis of the biofilm on the cathode indicated that the cathode was dominated by an Enterococcus species closely related to Enterococcus aquimarinus.

In this paper, we report the fabrication of high aspect ratio, highly dense, very fine pitch on-chip copper-pillar-based interconnects for advanced packaging applications. Photoresist molds up to a thickness of 80 µm and having feature sizes as small as 5 µm were fabricated using multi-step coating of the positive tone AZ9260 photoresist. Spin coating and lithography parameters were optimized to achieve smooth and vertical sidewalls. Copper interconnects having an aspect ratio up to 6 and a pitch size of 25 µm were electroplated in the fabricated resist mold. Due to a very small pitch size, the total number of interconnects per cm2 chip area is 160 000, which is much larger than the conventional solder-based interconnects. The electrical resistance of the electroplated copper interconnects was measured by 4-probe kelvin measurement configuration and was found to be in the range of 8–10 mΩ and the corresponding electrical resistivity was calculated as 2.4 µΩ cm. Such low resistive interconnects can carry much larger electrical current without significant electrical loss, which is ideally suitable for next generation packaging applications. X-ray diffraction has shown the presence of the (2 2 0) texture along the length of electroplated copper pillars. Transmission electron microscope reveals the presence of nanoscale copper twins along the length of copper interconnects.

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