• Energy Research

Abstract High-performance harvesting of waste heat energy and its conversion into electric energy via thermo-electrochemical cells is an essential strategy of renewable energy development. Even though there is a large amount of scientific research available, but due to expensive electrode materials and low efficiency, the thermo-electrochemical cells have not found practical application. Here we demonstrated thermo-electrochemical cell with nickel (Ni) hollow microspheres-based electrodes, provided the highest hypothetical Seebeck coefficient of 4.5 mV/K (for aqueous electrolyte based thermocells) until today and open-circuit voltage values of up to 0.2 V. High values of Seebeck coefficient provide the ability to collect low-temperature heat, and high output potential differences which allow to fabricate batteries for commercial power circuits for various microelectronic devices. This work also proposed a mechanism and science behind the electrode processes, which explains a extremely high values of the hypothetical Seebeck coefficient. This is the first time to use Ni hollow microsphere in thermo-electrochemical cell for heat harvesting and thermal energy conversion into electricity. Because of the low cost of Ni microspheres electrode-based developed thermo cells could be commercially feasible for harvesting low-quality thermal energy.

Low-grade waste heat harvesting and conversion into electric energy is an important way of renewable energy development and thermo-electrochemical cells are promising devices to solve this problem. In this paper, we report original data on the current density and maximum output power dependents on voltage of the thermos-cells with nickel hollow microspheres electrodes and different electrolyte concentration (from 0.1 to 3.0 mol/l)which exhibit excellent hypothetical Seebeck coefficient and accordingly high open-circuit voltage values at low source temperature. The composition, microstructure and morphology of the hollow nickel microspheres based electrodes are included here. Because of the low cost of nickel based thermo-cells could be commercially feasible for harvesting low-quality thermal energy, in this connection, the raw data of measurements of their properties are given here. The data is related to "High Seebeck coefficient thermo-electrochemical cell using nickel hollow microspheres electrodes", Burmistrov et al., Renewable Energy, 2020 [1].

The nanoscale morphology and mesoporosity have a substantial effect on the energy storage properties because they offer a high surface area and porous nature. The former one bestows the accessibility of more redox-active sites, while the latter facilitates the easy entry of foreign atoms. In this report, we rationally synthesized the mesoporous NiO–SiO2 material with hetero-morphologies by a simple wet-chemical method, followed by calcination. The hetero-morphologies include nanospheres, nanoflakes, and nanoparticles collectively increased the surface area. To further increase the redox activity, the cobalt was hydrothermally doped to the NiO–SiO2 material (Co@NiO–SiO2). Consequently, the Co@NiO–SiO2 electrode demonstrated superior electrochemical response with a higher capacity of 41.7 μAh cm−2 compared to the NiO–SiO2 electrode (25 μAh cm−2) in a three-electrode system. Moreover, the Co@NiO–SiO2 electrode was sustained up to 10,000 cycles by retaining 95.5% of its initial capacity. The ability of the Co@NiO–SiO2 material towards practical applicability was also unveiled by fabricating a hybrid supercapacitor (HSC). The HSC delivered a notable energy density (42.3 μWh cm−2) and power density (10.2 mW cm−2). Furthermore, the HSC exhibited outstanding durability (10,000 cycles) without fading. The ability of HSC was also tested by energizing light-emitting diodes.

As the primary greenhouse gas, CO2 emission has noticeably increased over the past decades resulting in global warming and climate change. Surprisingly, anthropogenic activities have increased atmospheric CO2 by 50% in less than 200 years, causing more frequent and severe rainfall, snowstorms, flash floods, droughts, heat waves, and rising sea levels in recent times. Hence, reducing the excess CO2 in the atmosphere is imperative to keep the global average temperature rise below 2 °C. Among many CO2 mitigation approaches, CO2 capture using porous materials is considered one of the most promising technologies. Porous solid materials such as carbons, silica, zeolites, hollow fibers, and alumina have been widely investigated in CO2 capture technologies. Interestingly, porous silica-based materials have recently emerged as excellent candidates for CO2 capture technologies due to their unique properties, including high surface area, pore volume, easy surface functionalization, excellent thermal, and mechanical stability, and low cost. Therefore, this review comprehensively covers major CO2 capture processes and their pros and cons, selecting a suitable sorbent, use of liquid amines, and highlights the recent progress of various porous silica materials, including amine-functionalized silica, their reaction mechanisms and synthesis processes. Moreover, CO2 adsorption capacities, gas selectivity, reusability, current challenges, and future directions of porous silica materials have also been discussed.