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In this work, waste cooking palm oil (WCPO)-based carbon nanotubes (CNTs) with encapsulated iron (Fe) nanoparticles have been successfully produced via modified thermal chemical vapor deposition method. Based on several characterizations, the dense WCPO-based CNT was produced with high purity of 89% and high crystallinity proven by low ID/IG ratio (0.43). Moreover, the ferromagnetic response of CNTs showed that the average coercivity and magnetization saturation were found to be 551.5 Oe and 13.4 emu/g, respectively. These produced WCPO-based CNTs were further used as heavy metal ions adsorbent for wastewater treatment application. Some optimizations, such as the effect of different adsorbent dosage, varied initial pH solution, and various heavy metal ions, were investigated. The adsorption studies showed that the optimum adsorbent dosage was 1.8 g/L when it was applied to 100 mg/L Cu (II) solution at neutral pH (pH 7). Further measurement then showed that high Cu (II) ion removal percentage (~80%) was achieved when it was applied at very acidic solution (pH 2). Last measurement confirmed that the produced WCPO-based CNTs successfully removed different heavy metal ions in the following order: Fe (II) > Zn (II) ≈ Cu (II) with the removal percentage in the range of 99.2 to 99.9%. The adsorption isotherm for Cu (II) was better fitted by Langmuir model with a correlation coefficient of 0.82751. WCPO-based CNTs can be a potential material to be applied as adsorbent in heavy metal ion removal.

In this work, sand/zinc oxide (ZnO)/titanium dioxide (TiO2)-based photocatalysts were hybridized with graphene oxide (GO) and GO_multi-walled carbon nanotubes (MWCNTs) hybrid solution. The novel hybrid was then used in photocatalysis to degrade dye contamination. The nanocomposite photocatalyst was initially fabricated by growing ZnO nanorods (NRs) via sol-gel immersion followed by synthesizing TiO2 NRs for different times (5 and 20 h) using a hydrothermal method on sand as a substrate. Prior to the hybridization, the initial GO was synthesized using electrochemical exfoliation and further mixed with 1 wt% MWCNTs to form GO_MWCNTs hybrid solution. The synthesized GO and GO_MWCNTs hybrid solution were then incorporated onto sand/ZnO/TiO2 nanocomposite-based photocatalysts through immersion. Various sand/ZnO/TiO2-based photocatalysts were then tested for methylene blue (MB) dye degradation within 3 days. On the basis of UV-Vis measurement, the highest MB degradation was achieved by using sand/ZnO NRs/TiO2 NRs (5 h)/GO_MWCNTs (92.60%). The high surface area and high electrical conductivity of GO_MWCNTs prolonged the lifetime of electron/hole separation and thus enhanced the photocatalytic performance.

In this work, sand/zinc oxide (ZnO)/titanium dioxide (TiO

Hybrid organic–inorganic perovskite (HOIP) photovoltaics have emerged as a promising new technology for the next generation of photovoltaics since their first development 10 years ago, and show a high-power conversion efficiency (PCE) of about 29.3%. The power-conversion efficiency of these perovskite photovoltaics depends on the base materials used in their development, and methylammonium lead iodide is generally used as the main component. Perovskite materials have been further explored to increase their efficiency, as they are cheaper and easier to fabricate than silicon photovoltaics, which will lead to better commercialization. Even with these advantages, perovskite photovoltaics have a few drawbacks, such as their stability when in contact with heat and humidity, which pales in comparison to the 25-year stability of silicon, even with improvements are made when exploring new materials. To expand the benefits and address the drawbacks of perovskite photovoltaics, perovskite–silicon tandem photovoltaics have been suggested as a solution in the commercialization of perovskite photovoltaics. This tandem photovoltaic results in an increased PCE value by presenting a better total absorption wavelength for both perovskite and silicon photovoltaics. In this work, we summarized the advances in HOIP photovoltaics in the contact of new material developments, enhanced device fabrication, and innovative approaches to the commercialization of large-scale devices.

This work investigated the effect of post-annealing treatment on the fabrication of zinc oxide (ZnO) thin film by spraying deposition method. Based on SEM analysis, the annealed ZnO thin film at 400˚C presented better uniformity as compared to the non-annealed film. Further measurement by UV-Vis revealed that the lowest optical band gap energy (Eg) (3.22 eV) was achieved by 400˚C sample. These results confirmed that post-annealing treatment enhanced the optical and morphological properties of the fabricated ZnO thin film.

Dye sensitized solar cells (DSSCs) merupakan teknologi alternatif fotovoltaik yang menguntungkan. DSSCs menunjukkan harga yang murah, efisiensi yang tinggi dan proses pembuatan yang sederhana. Dalam aplikasi DSSCs, fotoanoda memiliki peranan yang penting untuk mengumpulkan elektron-elektron yang tereksitasi dan dye berfungsi untuk menyalurkan cahaya elektron-elektron ke transparent conducting film (TCF). Fotoanoda mempunyai band gap yang lebar pada semikonduktor logam oksida (contoh: zinc oxide (ZnO) dan titanium dioxide (TiO2)) yang dilapiskan pada TCF. Counter electrode (CE) adalah salah satu komponen yang penting dalam proses kerja DSSCs. CE digunakan sebagai mediator untuk membangkitkan sensitizer setelah masuknya elektron. Bahan CE yang ideal harus mempunyai resistansi yang rendah, biaya produksi yang murah, konduktivitas listrik yang tinggi, aktivitas elektrokatalitik yang bagus dan stabilitas yang tinggi. Bahan-bahan CE yang umum digunakan untuk aplikasi DSSCs yaitu seperti platina (Pt), karbon, carbon nanotubes (CNTs), grafin dan polimer konduktif. Review ini dikembangkan untuk mempelajari sifat-sifat bahan fotoanoda dan CE yang bagus untuk aplikasi DSSCs. Review ini juga digunakan untuk memberikan informasi untuk perkembangan bahan-bahan fotoanoda dan CE pada penelitian selanjutnya dalam aplikasi DSSCs. Dalam review ini, pengaruh bahan-bahan yang digunakan untuk fotoanoda dan CE dalam aplikasi DSSCs didiskusikan.