Md. Mehedi Hasan

Advances in Photocatalytic CO2 Reduction with Water: A Review

In recent years, the increasing level of CO2 in the atmosphere has not only contributed to global warming but has also triggered considerable interest in photocatalytic reduction of CO2. The reduction of CO2 with H2O using sunlight is an innovative way to solve the current growing environmental challenges. This paper reviews the basic principles of photocatalysis and photocatalytic CO2 reduction, discusses the measures of the photocatalytic efficiency and summarizes current advances in the exploration of this technology using different types of semiconductor photocatalysts, such as TiO2 and modified TiO2, layered-perovskite Ag/ALa4Ti4O15 (A = Ca, Ba, Sr), ferroelectric LiNbO3, and plasmonic photocatalysts. Visible light harvesting, novel plasmonic photocatalysts offer potential solutions for some of the main drawbacks in this reduction process. Effective plasmonic photocatalysts that have shown reduction activities towards CO2 with H2O are highlighted here. Although this technology is still at an embryonic stage, further studies with standard theoretical and comprehensive format are suggested to develop photocatalysts with high production rates and selectivity. Based on the collected results, the immense prospects and opportunities that exist in this technique are also reviewed here.

Multi band negative index metamaterial based on split square shape resonators

A multi band negative index metamaterial based on split square shape resonators has been discussed in this paper. The proposed metamaterial unit cell structure is a combination of split square shape ring resonators. Commercially available electromagnetic simulator CST Microwave Studio has been used to investigate the calculation of the proposed design. The proposed structure shows resonance at 3.36 GHz, 5.98 GHz, 9.83 GHz, 13.10 GHz and exhibits negative index characteristics at 8.25 GHz. The effective medium ratio of the designed unit cell is 8.90. However, a performances comparison analysis has been done between Rogers RT 5880 and Teflon substrate materials.

Left-handed metamaterial inspired by joint T-D geometry on flexible NiAl2O4 substrate

In this paper, we introduce a new compact left-handed tunable metamaterial structure, inspired by a joint T-D shape geometry on a flexible NiAl2O4 substrate. The designed metamaterial exhibits an extra-large negative refractive index bandwidth of 6.34 GHz, with an operating frequency range from 4 to 18 GHz. We demonstrate the effects of substrate material thickness on the effective properties of metamaterial using two substrate materials: 1) flame retardant 4 and 2) flexible nickel aluminate. A finite integration technique based on the Computer Simulation Technology Microwave Studio electromagnetic simulator was used for our design, simulation, and investigation. A finite element method based on an HFSS (High Frequency Structure Simulator) electromagnetic simulator is also used to simulate results, perform verifications, and compare the measured results. The simulated resonance peaks occurred at 6.42 GHz (C-band), 9.32 GHz (X-band), and 16.90 GHz (Ku-band), while the measured resonance peaks occurred at 6.60 GHz (C-band), 9.16 GHz (X-band) and 17.28 GHz (Ku-band). The metamaterial structure exhibited biaxial tunable properties by changing the electromagnetic wave propagation in the y and z directions and the left-handed characteristics at 11.35 GHz and 13.50 GHz.

Left-Handed Network-Shaped Metamaterial for Visible Frequency

In this paper, a network-shaped left-handed metamaterial for visible frequency applications has been presented. The proposed metamaterial is designed on the epoxy resin composite with woven glass fibre by a complex structure is driven by the average connectivity of the metallic network. Finite integration technique-based electromagnetic simulator Computer Simulation Technology Microwave Studio has been utilized to design, simulation and purpose of the proposed design. The designed structures exhibit resonance at 104.95, 140.61, 164.2 and 195.19 THz as well as the left-handed characteristics at 182 THz. Finally, the structure is also analysed by rotating 22.5°, 45°, 67.5° and 90°, respectively, in the xy-plane for observing the rotation effects on the result of the reflection (S11) and transmission (S21) coefficient.

A Terahertz Meta-Surface with Left-Handed Characteristics for Absorbing Applications

A meta-surface that absorbs waves from all directions of incidence can be realized if the surface impedance is made to vary as a function of incidence in a specific manner. In this paper, a terahertz meta-surface with left-handed characteristics for high absorbing applications is discussed. The designed small absorber unit was developed by cross-metallic connection of two metal strips printed on epoxy resin fibre material. Finite integration technique-based electromagnetic simulator Computer Simulation Technology Microwave Studio was utilized to simulate and investigate the proposed design. The proposed meta-surface shows resonance at 39.19 THz, 58.47 THz and 77.80 THz and left-handed characteristics at 15.3 THz and 87.7 THz respectively. In addition, the structure of the absorber shows the highest absorption peaks of 99.6% and 89.5% at 16.4 THz and 75.8 THz respectively.

A Compact SWB Antenna Using Parasitic Strip

A compact super-wideband (SWB) antenna has been presented based on parasitic strip in this paper. The radiating patch of the antenna is constructed by the circular disc fed with a microstrip line and parasitic strip on the ground plane. This antenna has been fabricated on 1.60-mm-thick epoxy resin fibre material where the total dimension of the antenna is 25 mm × 33 mm. High-frequency structural simulator has been adopted for performing all the simulations and analysis. The 17.10 GHz (from 2.90 to 20 GHz) impedance bandwidth is achieved in the measurements with the stable gain (3.2–6.22 dBi) through the proposed antenna.