Density Functional Theory Studyof Water Adsorption on the CoO (100) and CoO (110) Surfaces

The density functional theory (DFT) method was used in this study to determine the chemical and physical properties of Cobalt Oxide (CoO) because it is a reliable, fast and inexpensive technique. This study is designed to determine the electronic properties of CoO bulk and the adsorption energy of the water molecule (H2O) on the CoO surface. CoO crystals used in this study have been optimized by using the GGA-PBE and LDA-CAPZ methods. The study found that calculations using GGA-PBE were closer to the experiment value. Without considering spin orbital interactions, CoO showed a metallic electronic band structure. After considering the spin orbital interaction calculation, each alpha and beta band structures has band gap of 1.55 eV, which is similar to the reported theoretical value. The ground state of CoO is antiferromagnetic base-on alpha and beta band structures. The peak absorption of light representing optical properties at wavelength energy is 351 nm in visible light spectrum (UV) range. The DFT calculation is used to determine the H2O adsorption energy to the surfaces of CoO (100) and CoO (110). H2O adsorption energy on CoO (100) and CoO (110) surfaces is based on eight different configurations, with different H2O adsorption positions on each CoO surface. On the CoO (100) surface, H2O adsorption energy is optimum in Model 5, with a value of 5.123 eV. Meanwhile, the H2O adsorption energy on the CoO (110) surface is optimum in Model 6, with a value of 2.810 eV. Based-on adsorption energy study, it expected that H2O easier to absorb on CoO(110) rather than on CoO(100)

Density functional theory study on the electronic properties of doped-cobalt oxide (CoO)

Cobalt oxide (CoO) has been widely studied for photocatalyst of water splitting and displaying a high-efficiency material. This paper reports a Density Functional Theory (DFT) study on the electronic properties of rock-salt CoO and analyzes effects of cations (Ni and Fe) and anions (N and F) dopants on the electronic properties. For this purpose, CASTEP software used for first principles plane-wave pseudo-potential calculations at different functional, i.e: GGA-PW91 and LDA. The electronic calculations of the CoO optimized structure showed a metallic structure if without considering spin-orbital interactions. After considering the spin-orbital interaction calculation, the CoO band structure possessed indirect and direct band gaps. The direct bandgap by GGA-PW91 calculation is 2.10 eV, it was agreed to the experimentally reported value of approximately 1.9-2.6 eV. Meanwhile, Ni, Fe, and F-doped CoO, demonstrating decreased CoO direct band gaps to 1.70 eV, 1.80 eV, and 1.73 eV, respectively. While N-doped CoO increased the CoO direct bandgap to 3.05 eV. All dopants shifted the conduction and valence bands position, where Ni-doped CoO band edges keep straddle to the redox potential of water splitting. Among other elements in this study, Ni is a more desirable dopant of CoO to enhance photoelectrochemical hydrogen production

Sintesis, pencirian spektroskopi dan sifat fotomangkin Rutenium(II) Bis(bipiridil)-2-(1H-pirazol-3-il)piridil

Kompleks Ru(II), [Ru(bpy)2(pypzH)](PF6)2 dengan bpy = 2,2’-bipiridil dan pypzH= 2-(1H-pirazol-3-il)piridin, telah berjaya disintesis dan dicirikan dengan teknik spektroskopi transformasi Fourier inframerah (FTIR), ultralembayung dan cahaya nampak (UV-Vis), resonans magnet nukleus (RMN), serta spektrometer jisim. Pengiraan dengan kaedah teori fungsi ketumpatan (DFT) dan DFT bersandar masa (TD) telah dijalankan untuk membangunkan struktur optimum dan elektronik kompleks Ru(II). Data yang diperoleh menunjukkan orbital molekul terisi dengan tenaga tertinggi (HOMO) disetempatkan pada logam Ru(II) dan ligan pypzH, manakala orbital molekul tidak terisi dengan tenaga terendah (LUMO) didapati tersebar secara menyeluruh pada kedua-dua struktur ligan bpy. Aktiviti fotomangkin kompleks telah diuji terhadap penguruaian pewarna tekstil bromotimol biru (BTB) disebabkan aktiviti foto [Ru(bpy)2(pypzH)](PF6)2 di bawah sinaran lampu xenon 450W (AM 1.5, penapis inframerah). Kadar dan tertib tindak balas foto-uraian BTB dikenal pasti dan dibincangkan bersama dengan mekanisma foto-uraian BTB

Induced roll magnetic separator applied for high grade ilmenite separation from mining tailing

This article aimed to separate ilmenite (FeTiO3) mineral from tin tailing applying a single splitter IRMS (Induced Roll Magnetic Separator). Ilmenite mineral is the substantial main source for TiO2. This work used air table middling for feeding. The mineral components of middling feeding from air table using grain counting analysis were found as follows: cassiterite (48.61%), ilmenite (21.36%), monazite (18.56%), pyrite (4.60%), zircon (5.85%), quartz (0.71%), anatase (0.27%), and tourmaline (0.02%), It was found that electrical current and opening of single splitter affected the degree of separation addressing to ilmenite recovery and ilmenite grade. The finding showed that current of 15 Ampere and single splitter with opening 4.25 cm yielded ilmenite recovery more than 74%. The high grade ilmenite (90.46 %) and recovery of 29.38% was obtained using 5 Ampere  with single splitter opening of 1.0 cm. Up to date, the study on ilmenite separation from tailing only focused on the effect of current, however, the effect of single splitter magnetic separator  to enhance ilmenite recovery from other paramagnetic minerals such as monazite, siderite, xenotime and tourmaline has not yet been reported.

Synthesis, structure and spectroscopic properties of oxovanadium tris(3,5-dimethylpyrazolyl)borate aroylthiourea complexes

Aroylthiourea ligands, 1-aroyl-3-cyclohexyl-3-methylthiourea (HL1), 1-(2-chloroaroyl)-3-cyclohexyl-3-methylthiourea (HL2), 1-(3-chloroaroyl)-3-cyclohexyl-3-methylthiourea (HL3) and 1-(4-chloroaroyl)-3-cyclohexyl-3-methylthiourea (HL4) were synthesized through a condensation reaction of methylcyclohexylamine and aroylisothiocyanate with a general formula (X-Ph)(CO)NH(CS)N(C6H5)(CH3) where X = H, o-Cl, m-Cl and p-Cl, fully characterized by CHNS micro elemental analysis, infrared spectroscopy, UV-visible, nuclear magnetic resonance (1H, 13C) and X-ray crystallography. 1-(3-chloroaroyl)-3-cyclohexyl-3-methylthiourea (HL3) crystallized in the monoclinic system, a=14.504(3), b=4.9599(11), c=22.325(5) Å, β=98.461(7)°, Z= 4 and V=1588.5(6) Å with space group P21/c. The IR spectra of the ligands exhibits the characteristic v(CO) and v(N-H) at range 1701-1640 cm-1 and 3317-3144 cm-1, respectively. Whereas the 1H and 13C NMR spectra shows the resonances for N-H and -CO groups at range 8.3-8.5 and 160-163 ppm, respectively. A one-pot reaction involving the aroylthiourea ligand, oxovanadium(IV) ion and potassium hydrotris(3,5-dimethylpyrazolyl)borate (KTp*) complex gave the desired [oxovanadium(IV)(tris(pyrazolyl)borate)(aroylthiourea)] complexes namely Tp*VOL1, Tp*VOL2, Tp*VOL3 and Tp*VOL4 and all complexes were characterized accordingly. X-ray study showed that Tp*VOL1 adopted a monoclinic crystal, a=3.415(2), b=19.463(3), c=14.22(3) Å, β=107.411(4)°, Z= 4 and V=3542.7(11) Å with P21/c space group. The VO2+ center adopted a pseudo-octahedral geometry O2N3S, with the oxovanadium(IV) coordinated to the bidentate ligand (X-Ph)(CO)NH(CS)N(C6H5)(CH3) and tridentate Tp* ligands. The results showed that aroylthiourea ligands behave as bidentate chelate through O and S atom and the Tp* C3v symmetry adds stabilization to the VO2+ through its protective tripodal geometry

Experimental and theoretical study of Cu2 O photoelectrode and Cu2 O doped with Ag, Co, Ni and Zn metals for water splitting application

In the present study, cuprous oxide nanowire fabricated using wet chemical oxidation method was proven to produce high photoactive film for photoelectrochemical (PEC) water splitting. A relatively high photocurrent density of -5mA cm-2 at 0.6V vs Ag/AgCl was generated. The PEC performance is the reflection of intrinsic light absorption capacity at visible region which correspond to 2.0eV, an ideal band gap for PEC water splitting. Comparison with calculated data based on density functional theory using CASTEP shows that the band gap and light absorption capacity obtained from experimental work exhibited a close match. Hence, this study suggested that the preparation of Cu2 O thin film via wet chemical oxidation method obeyed the theoretical prediction. However, the Cu2 O is limited with poor stability in PEC condition attributed to the insufficient potential of its valence band to oxidize water. Therefore, an effort was directed to address the feasibility of shifting the valence band by modeling a doped Cu2 O with several dopants using DFT technique. The selected dopants were Ag, Co, Ni and Zn. Preliminary conclusion of this study indicated that doping could be used to tune the band gap of Cu2 O due to ionic radii of the dopant affected the shifting of band gap. In this study, Co showed more significant improvement of Cu2 O for photoelctrochemical water splitting process. However, to validate the simulation, further study should be carried out experimentally

Hydrogen production from water splitting using TiO2 /CoS composite photocatalyst

Photocatalytic water splitting reaction has been considered an ideal method for hydrogen generation. In this study, a composite of TiO2 /CoS photocatalyst prepared by hydrothermal synthesis method assisted by ball milling crushing process was used. The TiO2 /CoS composites prepared with three variation compositions of 90/10, 80/20, and 70/30 were named M-10, M-20, and M-30, respectively. Field-emission scanning electron microscopy images showed that the morphologies of the composites were porous and uniform of nanospheres. The X-ray diffraction and energy dispersive spectroscopy analyses confirmed the presence of CoS in the composites. Ultraviolet–visible absorption characterization demonstrated the smallest bandgap value of approximately 2.72 eV presented by sample M-30 with the photocurrent density of 0.32 mA cm−2 at 0.9 V vs. Ag/AgCl. The presence of CoS in this study could increase the PC hydrogen generation of TiO2 by nearly 2.5 times. The composites forming a p-n heterojunction between TiO2 and CoS could prevent electron–hole recombination and increase the overall photoactivity of TiO2.

POTENSI DESA LEMAHDUHUR MENUJU PENCAPAIAN SUSTAINABLE DEVELOPMENT GOALS

Pencapaian tujuan pembangunan berkelanjutan (Sustainable DevelopmentGoals/SDGs) menghendaki partisipasi dari semua pihak. Begitu juga di desa,potensi yang dimiliki oleh desa dapat diarahkan pada pencapaian tujuanpembangunan berkelanjutan. Pengabdian kepada masyarakat ini dilakukanuntuk menginventarisasi data berkaitan dengan potensi desa Lemahduhur.Pemutakhiran data potensi desa dilakukan dengan membantu memperbaruidata pada profil desa dan kelurahan (Prodeskel). Desa Lemahduhur memilikipotensi sumber daya alam berupa lahan sawah penghasil padi yang cukupluas, potensi sumber daya manusia dengan mayoritas penduduk berada padausia produktif, potensi kelembagaan dan ekonomi dengan adanya BUMDessebagai usaha pengembangan ekonomi produktif, serta potensi sarana danprasarana yang dapat mendukung dalam pencapaian tujuan pembanguanberkelanjutan. Potensi tersebut hendaknya terus dikembangkan untukmemberikan manfaat bagi seluruh masyarakat desa. Alokasi dana desa yangtepat sasaran serta komunikasi dan koordinasi yang baik akan mendukungdalam pencapaian tujuan pembangunan berkelanjutan.Kata kunci—SDGs Desa, potensi desa, pengabdian kepada masyarakat Achieving the Sustainable Development Goals (SDGs) requires participationfrom all parties. Likewise, in the village, the village's potential can be directedtowards achieving the goals of sustainable development. This community serviceis carried out to inventory data related to the potential of Lemahduhur village.Updating the village potential data is carried out by helping to update the datain the village and sub-district profiles (Prodeskel). Lemahduhur Village has thepotential for natural resources in the form of quite extensive rice-producing ricefields, human resource potential with the majority of the population being ofproductive age, institutional and economic potential with the existence ofBUMDes as an effort to develop a productive economy, as well as potentialfacilities and infrastructure that can support in the achievement of sustainable development goals. This potential should continue to be designed to providebenefits to all village communities. The allocation of village funds that is righton target and good communication and coordination will support sustainabledevelopment goals.Keywords—village SDGs, village potential, community devotio

3D Free-standing graphene: influence of etching solution and etching time on chemical vapor deposition on the graphene/nickel foam

Three-dimensional (3D) structures made of graphene sheets have been developed recently, and have resulted in the development of a new class of graphene materials known as 3D graphene materials. High-quality free-standing 3D graphene foam has been synthesized by chemical vapor deposition (CVD) on nickel foam followed by a chemical etching process to remove the nickel foam as a template. Field-emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), and Raman spectroscopy measurements were performed to investigate the morphologies, crystal phase, and the structure of nickel foam (NF), graphene/nickel foam (Gr/NF), and 3D graphene (3D Gr). In this study, the influence of etching solution and etching time on Gr/NF to produce free-standing 3D Gr was investigated. XRD spectroscopy showed that the mixed solutions of 1M FeCl3:1M HCl at 80 °C for 3 h can significantly remove the NF and no peaks of NF are observed, thus indicating a high crystal quality of 3D Gr was obtained. In addition, XRD spectroscopy revealed that by increasing the etching time beyond 3 h, the intensity of diffraction peaks decreases, thus degrading graphene quality. This research emphasizes the significance of proper selections of etching solution and etching time in removing the NF to maintain the characteristic, quality, and surface morphology of 3D Gr after the etching process

Kesan pemendapan elektroforesis gam arab terhadap kakisan SS316 L dalam persekitaran asid

Keluli tahan karat jenis 316L (SS316L) adalah satu logam yang berpotensi untuk digunakan sebagai plat dwikutub bagi sel fuel membran pertukaran proton (PEMFC). SS316L memiliki sifat kekonduksian elektrik dan kepasifan yang baik, namun jika digunakan pada sekitaran asid (pH 3-6), sifat pelarutan SS316L akan menyebabkan mudah terhakis. Dalam kajian ini, salutan perencat kakisan hijau gam arab dengan kaedah pemendapan elektroforesis (EPD) digunakan untuk mengurangkan kakisan plat SS316L. Hasil analisis scaning electron microscope (SEM) menunjukkan permukaan SS316L lebih halus dan tebal, dengan ketebalan salutan antara 4.9 - 8.9 μm. Pengujian menggunakan kaedah polarisasi linear Tafel dalam media 0.5 M H2 SO4 , mendapati nilai arus kakisan (Icorr) semakin menurun dengan adanya salutan iaitu dari 18.484 μA/cm2 menjadi 0.859 μA/cm2 . Kadar kakisan SS316L tanpa salutan adalah 0.7172 mpy, manakala SS316L yang disalut dengan gam arab mempunyai kadar kakisan yang lebih rendah iaitu 0.033 mpy. Dari kajian ini, keputusan menunjukkan bahawa gam arab dengan salutan EPD dapat memberikan perlindungan kakisan terhadap permukaan SS316L