Prakash C. Ghosh

1D Copper Nanostructures: Progress, Challenges and Opportunities

One-dimensional noble metal nanostructures are important components in modern nanoscience and nanotechnology due to their unique optical, electrical, mechanical, and thermal properties. However, their cost and scalability may become a major bottleneck for real-world applications. Copper, being an earth-abundant metallic element, is an ideal candidate for commercial applications. It is critical to develop technologies to produce 1D copper nanostructures with high monodispersity, stability and oxygen-resistance for future low-cost nano-enabled materials and devices. This article covers comprehensively the current progress in 1D copper nanostructures, most predominantly nanorods and nanowires. First, various synthetic methodologies developed so far to generate 1D copper nanostructures are thoroughly described; the methodologies are in conjunction with the discussion of microscopic, spectrophotometric, crystallographic and morphological characterizations. Next, striking electrical, optical, mechanical and thermal properties of 1D copper nanostructures are highlighted. Additionally, the emerging applications of 1D copper nanostructures in flexible electronics, transparent electrodes, low cost solar cells, field emission devices are covered, amongst others. Finally, there is a brief discussion of the remaining challenges and opportunities.

Recent advances in the development and utilization of modern anode materials for high performance microbial fuel cells.

Microbial fuel cells (MFCs) are novel bio-electrochemical device for spontaneous or single step conversion of biomass into electricity, based on the use of metabolic activity of bacteria. The design and use of MFCs has attracted considerable interests because of the potential new opportunities they offer for sustainable production of energy from biodegradable and reused waste materials. However, the associated slow microbial kinetics and costly construction materials has limited a much wider commercial use of the technology. In the past ten years, there has been significant new developments in MFCs which has resulted in several-fold increase in achievable power density. Yet, there is still considerable possibility for further improvement in performance and development of new cost effective materials. This paper comprehensively reviews recent advances in the construction and utilization of novel anodes for MFCs. In particular, it highlights some of the critical roles and functions of anodes in MFCs, strategies available for improving surface areas of anodes, dominant performance of stainless-steel based anode materials, and the emerging benefits of inclusion of nanomaterials. The review also demonstrates that some of the materials are very promising for large scale MFC applications and are likely to replace conventional anodes for the development of next generation MFC systems. The hurdles to the development of commercial MFC technology are also discussed. Furthermore, the future directions in the design and selection of materials for construction and utilization of MFC anodes are highlighted.

Enhanced Thermal Conductivity of Copper Nanofluids: The Effect of Filler Geometry

Nanofluids are colloidal dispersions that exhibit enhanced thermal conductivity at low filler loadings and thus have been proposed for heat transfer applications. Here, we systematically investigate how particle shape determines the thermal conductivity of low-cost copper nanofluids using a range of distinct filler particle shapes: nanospheres, nanocubes, short nanowires, and long nanowires. To exclude the potential effects of surface capping ligands, all the filler particles are kept with uniform surface chemistry. We find that copper nanowires enhanced the thermal conductivity up to 40% at 0.25 vol % loadings; while the thermal conductivity was only 9.3% and 4.2% for the nanosphere- and nanocube-based nanofluids, respectively, at the same filler loading. This is consistent with a percolation mechanism in which a higher aspect ratio is beneficial for thermal conductivity enhancement. To overcome the surface oxidation of the copper nanomaterials and maintain the dispersion stability, we employed polyvinylpyrrolidone (PVP) as a dispersant and ascorbic acid as an antioxidant in the nanofluid formulations. The thermal performance of the optimized fluid formulations could be sustained for multiple heating-cooling cycles while retaining stability over 1000 h.

Comparison of coagulation, ozone and ferrate treatment processes for color, COD and toxicity removal from complex textile wastewater

In this study, the comparative performance of coagulation, ozone, coagulation + ozone + coagulation and potassium ferrate processes to remove chemical oxygen demand (COD), color, and toxicity from a highly polluted textile wastewater were evaluated. Experimental results showed that ferrate alone had no effect on COD, color and toxicity removal. Whereas, in combination with FeSO4, it has shown the highest removal efficiency of 96.5%, 83% and 75% for respective parameters at the optimal dose of 40 mgL-1 + 3 ml FeSO4 (1 M) in comparison with other processes. A seed germination test using seeds of Spinach (Spinacia oleracea) also indicated that ferrate was more effective in removing toxicity from contaminated textile wastewater. Potassium ferrate also produces less sludge with maximum contaminant removal, thereby making the process more economically feasible. Fourier transform infrared spectroscopy (FTIR) analysis also shows the cleavage of the chromophore group and degradation of textile wastewater during chemical and oxidation treatment processes.

Modelling and simulation of a PV battery grid backup system for various climatic zones of India

India has five climatic zones and the performances of renewable PV-battery systems in these zones vary widely. In literature where PV battery systems are simulated, only generic battery models are used which ignores the effect of temperature on battery performance. We extend these approaches to incorporate the thermal behavior of battery which helps in better predicting the performance, life and viability of microgrids powered by renewable sources with battery storage under different ambient conditions. In this present work, the influence of different climatic zones in India on the lifetime of the Pb-acid battery integrated with PV is simulated. Moreover, the life cycle costing is computed based on the lifetime to understand the viability of PV battery backup to grid in different climatic zones.

Life cycle costing of a self-sufficient solar-hydrogen system

In a renewable energy-based system, energy storage must match the energy demand with supply. Usually a lead-acid battery is utilised as a short-term energy buffer. A system, which has a combination of an electrolyser and a high-pressure hydrogen tank for long-term energy storage, is considered in this paper. The cost intensive components are sized considering the least cost and by performing a life cycle costing of the system. The optimum battery capacity obtained is 19 kWh, which is equivalent to 2.2 days of autonomy. At present, energy storage cost in the long-term storage is found 2.16 per kWh whereas the cost goes down to 0.92 per kWh when the target cost of the fuel cell and the electrolyser is considered. Around 15–20% of the demand is supplied by the long-term storage.

Catalytic ozone pretreatment of complex textile effluent using Fe 2+ and zero valent iron nanoparticles

The study investigates the effect of catalytic ozone pretreatment via Fe2+ and nZVI on biodegradability enhancement of complex textile effluent. The nZVI particles were synthesized and characterized by XRD, TEM and SEM analyses. Results showed that nano catalytic ozone pretreatment led to higher biodegradability index (BOD5/COD = BI) enhancement up to 0.61 (134.6%) along with COD, color and toxicity removal up to 73.5%, 87%, and 92% respectively. The disappearance of the corresponding GCMS & FTIR spectral peaks during catalyzed ozonation process indicated the cleavage of chromophore group and degradation of organic compounds present in the textile effluent. Subsequent aerobic biodegradation of nZVI pretreated textile effluent resulted in maximum COD and color reduction of 78% and 98.5% respectively, whereas the untreated effluent (BI = 0.26) indicated poor COD and color reduction of only 31% and 33% respectively. Bio-kinetic parameters also confirmed the increased rate of bio-oxidation at enhanced BIs. Seed germination test using seeds of Spinach (Spinacia oleracea), indicated the effectiveness of nano catalyzed ozone pretreatment in removing toxicity from contaminated textile effluent.

High platinum cost: obstacle or blessing for commercialization of low-temperature fuel cell technologies

Polymer electrolyte fuel cells (PEFCs), at the early stage of their commercialization, possess potential for different applications. Analogous to any other new technologies, PEFC technology is also facing several challenges and uncertainties during precommercialization phase. Platinum, used as the catalyst in PEFCs, is considered as one of the key obstacles towards the commercialization as it contributes significantly to the overall cost. In the present work, a life-cycle cost analysis is carried out based on the annual growth in the platinum price and the discount rate based on the local market for different economic zones. It is observed that the high investment in platinum could be beneficial instead of acting as the hurdle if the salvage value of platinum is considered. Based on the platinum cost per kW of the fuel cell, two different scenarios (32 and 3 US

Life cycle analysis of battery technologies for photovoltaic application in India

kW−1) are considered. It is observed that in spite of very high cost of platinum, the net present value of the fuel cell is comparable with the scenario with low investment cost in platinum when the salvage value of platinum is considered. In some situations, the high investment cost in the platinum offers high salvage value leading to a profitable case. Hence, the high cost of platinum might promote the commercialization of the fuel cells if appropriate business model is in place.

Three Dimensional Computational Fluid Dynamics Modelling of High Temperature Polymer Electrolyte Fuel Cell

Growing energy needs and the depleting nature of the nonrenewable sources demand the intervention of renewable sources and storage technologies which are sustainable. It is therefore desirable to perform sustainability analysis in terms of energy efficiency for electrochemical storage systems. This paper is concerned with life cycle energy analysis of batteries used for photovoltaic application in Indian context. The analysis is based on real production and transportation data for India, making it first of its kind to be presented to the technical community. The material production energy contributes about 50–75% of the total energy requirement of the life cycle of the battery. Transportation Energy has a significant contribution for Lithium Ion battery. The significance of manufacturing and recycling energy is specific to the battery technology.