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We report a new direct fabrication of the ZnO nanorods (NR) by hydrothermal method, in which the preparation of seed layer is eliminated. We show that the tuning of initial temperature rate during the hydrothermal process plays a key role in the structural modification of the ZnO NR. A highly oriented ZnO NR is successfully fabricated by using a low rate of initial temperature. The increase of optical absorption and electron transport was obtained by reducing the diameter and increasing distribution of the ZnO NR on the substrate. Interestingly, an additional absorption from the defects is obtained in the system, which plays an important role in expanding the optical absorption. Our system will provide a favourable characteristic for developing the high-performance optoelectronic devices with high optical absorption and high electron transport.

The aim of this research is to investigate the photodegradation of Methylene Blue with Fe3O4/ZnO core-shells. Fe3O4/ZnO core-shells were synthesized by a simple two-step chemical method (co-precipi...

Rock art comprises various forms of images and markings, including paintings, drawings, and engravings, created by prehistoric people on immobile surfaces of rocks. In Indonesia, the distribution of rock art sites has been relatively well studied and documented. Indeed, Uranium-series analysis of speleothem materials overlying negative hand stencils and naturalistic animal paintings from the limestone karsts of Maros in southern Sulawesi shows that the rock art in this region dates to at least 40,000 years ago, and is thus among the world's oldest. To our knowledge, the chemistry of the Sulawesi rock art, including that of the pigments used for making these images, and with particular regard to the topology and morphology of these materials, have not yet been systematically investigated. In this study, we report the results of our spectroscopic and microscopic analyses of two samples of pigment collected from rock art motifs at Leang Sumpang Bita 2 in Pangkep, South Sulawesi. The first and second samples possess dark red and purple colours, respectively. Analysis shows that both samples contain iron oxide, which may explain their reddish colours. Nevertheless, microstructural differences are evident, including crystal morphology and size, and, in our view, are responsible for the discrepancy in the observed pigment colours. Our findings suggest that the sampled dark red and purple pigments are from the same raw material source (ochre), but differ in colour because of mechanically-induced alteration, presumably the result of varying pigment-processing methods used by the prehistoric artists.

Efforts to reduce carbon dioxide (CO2) emissions remain elusive due to the strong correlation with economic development. The progress of economic development therefore needs to be assessed by considering the harmful effects of CO2 emissions as a loss of intergenerational well-being. This has been the motivation behind the development of the inclusive wealth (IW) index, which is proposed as a viable alternative to the conventional gross domestic product for tracking the progress towards the well-being of a nation. By using nonparametric machine learning methods, this study aims to explore the impact of CO2 emission reduction on well-being under the IW framework via three different energy pathways, namely, the supply, mix and efficiency pathways, involving 105 countries from 1992 to 2014. Results showed that the lowest growth in global CO2 emissions was projected by the efficiency scenario, which forecasted an increase by 2040 of 15.12% relative to the 2014 level. However, this scenario might lead to a potential loss in future well-being by up to 0.3%, compared to the two other scenarios. These findings suggest that the commitment to CO2 emission reduction needs to be evaluated cautiously by considering its impact on intergenerational well-being, particularly for developing economies. In contrast, high-income economies were encouraged to set up a more ambitious target of CO2 emission reduction since doing so would also lead to a potential increase of their intergenerational well-being. This study verifies a robust link between sustainable development and CO2 emission mitigation scenarios, which is essential for promoting future climate actions.

A cuttlefish bone contains Ca of 96.24% that is highly potential to be used in HA production. This study is focused to synthesize the HA by using starting materials of Ca(OH)2 from cuttlefish bone. A sonochemical method was implemented for preparing the HA/CS composites. The composition of HA/CS composites was maintained with a ratio of 90:10, 80:20, 70:30, and 60:40 (in %wt.). The synthesized of HA has a crystal size of 25.40 nm and the Ca/P ratio of 1.67. The XRD analysis showed that the increase of the chitosan content change crystal size of HA and HA/CS composites in nano-scale.

Increasing the efficiency of the household sector's energy consumption plays a significant role in reducing CO2 emissions, particularly for Indonesia, the world's fourth most populous country. However, there is a lack of analytical studies on the driving forces of emissions from the household sector in Indonesia, including the contribution of one of the world's largest efforts to promote a cleaner cooking fuel program. We intend to examine the characteristics of the Indonesian energy matrix and its evolution in the household sector alongside the impact of kerosene to the Liquid Petroleum Gas (LPG) conversion program to the Indonesian emissions change in the sector. We also investigate the underlying determinant of emissions change, both directly and indirectly, from household energy consumption in Indonesia from 2000 to 2015. For this purpose, we conduct the Logarithmic Mean Divisia Index (LMDI) decomposition analysis. We found that population and income led to increases of both direct and indirect energy emission, while the impact of energy intensity was the opposite. The fuel mix and carbon intensity effect, which reflects the conversion of kerosene to LPG, contributes to reducing direct emissions with limited effect. High share growth of coal in electricity generation led to increasing indirect emissions for the period. Our findings have important policy implications, particularly for increasing the share of new and renewable energy in the national energy mix and for intensifying energy efficiency in the household sector.

To meet the Paris Agreement’s climate mitigation objectives, there is an urgent global need to reduce coal combustion. Yet coal usage, particularly in the power sector, is rising in many developing countries. Indonesia is a notable example. While government policy is widely considered as the principle driver of Indonesia’s increasing coal consumption, studies have largely overlooked the influence of socioeconomic forces. To understand these effects, we utilize a decomposition analysis to capture the individual effect of five drivers of coal consumption in Indonesia over 1965 to 2017: (1) the energy mix, (2) energy intensity of GDP, (3) population, (4) urbanization, and (5) urban incomes. Results show the energy mix has exerted the largest effect on coal consumption. In addition, by accounting for other socio-economic influences, we found that other less appreciated factors have contributed to rising coal consumption. In order of contribution these were the urban economic effect, the growing relative share of urban population, and the population increase itself in absolute terms. We thus demonstrate that the drivers of growing coal consumption are multi-faced, complex and intertwined. Our findings show that developing nations such as Indonesia share a need to decouple urban population growth and increasing per capita wealth from fossil fuel (and coal) emissions.

The main keys in developing solar cells are their optical absorption and electron transfer (optical conductivity) levels. To enhance these two characteristics, an electron transport layer (ETL) was added to the solar cell, which is used to prevent electron recombination. Zinc oxide nanorod (ZnO NR) is one of the potential ETL candidates in the new generation of solar cells due to its high electron transfer. To optimize the use of ZnO NR in new generation solar cells, we combine NR ZnO with graphene, into a hybrid ZnO NR/graphene system. Optical absorption and conductivity of hybrid ZnO NR/graphene were studied using spectroscopic ellipsometry. A significant change in ellipsometry spectra has been observed, which increases with a higher number of graphene in the hybrid systems. Furthermore, the role of graphene on the optical absorption and conductivity of hybrid systems was investigated through fittings by applying the effective medium approximation (EMA) model. This study will provide a good understanding of optical absorption and optical conductivity of hybrid ZnO NR/graphene, which is an important key in the development of high-performance new generation solar cells.

Fe2O3/ZnO heterojunction has attracted great attention due to the possibility of overcoming low Photoelectrochemical (PEC) cell efficiency the limitation of a single layer of semiconductor electrodes. The aim of this study is to investigate the effect of Fe2O3, ZnO and Fe2O3/ZnO films on PEC efficiency. The Fe2O3, ZnO and Fe2O3/ZnO films were fabricated by spin coating and doctor blade methods, respectively. All the films were characterized by XRD, SEM, and Cyclic Voltammetry (CV). Based on structural results, Fe2O3 and ZnO nanoparticles can grow well on the ITO substrate and they exhibit trigonal and hexagonal crystal structures, respectively. Moreover, we found that the PEC efficiency increases after ZnO are coated on Fe2O3 film. The combination of Fe2O3 and ZnO can effectively increase the separation of electrons and holes that can improve the photocatalytic activity of PEC cells based on the structural coordinates of their energy levels.

This paper explores the effects of economic growth, urbanization, industry, and trade openness on coal consumption in Indonesia over the period 1970–2015. To closely adhere to the Environmental Kuznets curve narratives, we consider coal consumption which has been scarcely explored in the EKC debate, as a proxy of environmental pressure. We estimate the autoregressive distributed lag (ARDL) method and confirm that the variables are cointegrated for long run linkage with the presence of structural breaks. The empirical evidence showed that economic growth, urbanization and trade openness increase coal consumption while decreasing share of secondary industry reduce it. We also verify the existence of environmental Kuznets curve. Having a vital role in the energy mix, Indonesia needs to restrain excessive coal consumption to enhance environmental quality. Our results also imply urbanization and trade openness are crucial factors on coal consumption. Consequently, it should be taken into consideration in energy policy-making process, such as energy conservation policies in the residential sector and prioritize foreign investment which brings cutting-edge coal technologies.

We report on the effect of the morphological modification on optical properties and polarization of ZnO nanorods (NR). Here, the morphology and structure of the ZnO NR were modified by introducing different annealing temperatures. The increase of length and diameter and change in density of the ZnO NR were clearly observed by increasing the annealing temperature. We found that the samples show different oxygen vacancy (VO) and zinc interstitial (ZnI) concentrations. We suggest that the different concentrations of VO and ZnI are originated from morphological and structural modification. Our results reveal that optical absorption and polarization of ZnO NR could be enhanced by producing a high concentration of VO and ZnI. The modification of VO and ZnI promotes a decrease in the band gap and coexistence of high optical absorption and polarization in our ZnO NR. Our findings would give a broad insight into the morphological modification and characterization technique on ZnO NR. The high optical and polarization characteristics of ZnO NR are potential for developing the high-performance nanogenerator device for multitype energy harvesting.

We study electrical properties of ZnO thin films on p -Si (100) substrates as ultraviolet (UV) photodetector. ZnO films with thickness of ~400nm were deposited by room temperature (RT) DC unbalanced magnetron sputtering (DC-UBMS), and we also used ZnO film deposited at 260°C for the comparison. Metal-semiconductor-metal (MSM) planar structure was fabricated by using silver (Ag) contact on ZnO thin films as photodetector. X-ray diffraction (XRD) spectroscopy shows the amorphous structure of RT growth of ZnO thin films in contrast to relatively good crystallinity of ZnO film grown at 260°C. I-V characteristics of reverse-forward bias of UV photodetector were taken in dark and light conditions. As the results, amorphous phase of RT ZnO shows the high value of dark current and photocurrent. High stability of photo detection is also observable over the specific time as investigated by switching condition. In addition, we found that the mechanism of photo detection is strongly related to the oxygen adsorption on the ZnO surface. This study provides an alternative way to have a simple and high sensitive UV photodetector.

We study the effects of Ti doping on the near-band-edge emission (NBE) and defect-related deep-level emission (DLE) of ZnO thin films grown by DC unbalanced magnetron sputtering. DLE in pure ZnO is contributed by zinc and oxygen vacancies (VZn+VO), as revealed by photoluminescence (PL) spectroscopy, current–voltage (I–V) characteristic measurement, and spectroscopic ellipsometry. The reduction in the number of VZn states is clearly observed upon Ti doping, resulting in the enhancement of green emission from VO. Interestingly, the thin film with a Ti concentration of 1 at. % shows a higher excitonic emission. Furthermore, the temperature dependence of PL spectra shows that the enhanced excitonic emission originates from the donor-bound exciton promoted by the Ti dopant and native VO. This study shows an important role of the defects in controlling the optical and electronic properties of ZnO films for future optoelectronic applications.

We report on the influence of temperature on the polarization behavior of highly oriented ZnO thin film. First, the investigation of crystal structure change is studied, providing supporting information on the macroscopic-scale polarization of the ZnO thin film. Here, the lattice distortion is investigated by using X-ray diffraction. Furthermore, the role of temperature on the polarization behavior of the ZnO thin film is comprehensively studied by using temperature dependent spectroscopic ellipsometry. Here, the temperature dependent dielectric function analysis and electronic excitation models are used to understand the mechanism of polarization. We found an interesting temperature dependence of electronic transition, where the red-shift absorption and exciton-phonon interaction are observed on the system. This interaction is responsible for the increase of polarization response, which is confirmed by dielectric susceptibility spectra. These results provide important understanding for the control of the polarization dependence on the working temperature of ZnO thin film, which is the essential key in the fabrication of switchable optical devices.

We study the structural and optical properties of MoS2 nanoflakes on quartz substrate as prepared by mechanical exfoliation method. The structural and morphological properties of MoS2 nanoflakes were characterized by SEM, EDS, and XRD, while the high-resolution spectroscopic ellipsometry (SE) with the photon energy of 1.27 to 6.53 eV is used to study its optical characteristics. As the results, SEM data shows that MoS2 appears to be nanoflakes covering around 25-35% on the surface of quartz substrate, and XRD spectra shows the dominant orientation along c-axis (002). Based on spectroscopic ellipsometry analysis, the average thickness of MoS2 nanoflakes is around 12 nm or about 6-8 layers. By using Tauc plot method, we confirm that MoS2 nanoflakes have a semiconductor characteristic with the optical bandgap as high as 1.68 eV. Our study shows the important of structural and optical properties of MoS2 nanoflakes that can be utilized for future optoelectronic devices and energy-harvesting purposes.

We study the influence of Ti doping on the photodetection properties of zinc oxide (ZnO) thin films. The pure ZnO and ZnO:3%Ti (TZO) films were deposited on Si substrates by using DC-unbalanced magnetron sputtering. From the scanning electron microscopy (SEM) images, the TZO film grows more homogeneously in comparison with the pure ZnO structure. We suggest that Ti dopants play a role in uniformly distributing ZnO elements from the sputtering target to the Si substrate. The transmittance spectra of the Fourier transform infrared spectroscopy show a peak splitting of Zn–O stretching in the TZO film, which is also related to the dopant-modified film morphology. X-ray diffraction (XRD) spectra show that the Ti dopants also change the main ZnO crystal orientation from (0 0 2) to (1 0 3). The ZnO and TZO film-based photodetectors were fabricated by using a metal–semiconductor–metal planar configuration with Ag as the metal contact. Based on the I–V characteristics, Ti doping in the ZnO system reduces the dark current and induces the enhancement of the photo-to-dark-current ratio. Our study shows the important role of Ti doping on the improvement of photodetection performance.

We study plasmon–exciton interaction in ZnO-based thin film on bulk Pt by using high resolution spectroscopic ellipsometry. ZnO films on quartz are used as reference. This study shows the strong electronic interactions between ZnO film and Pt by considering the significant suppression of exciton in ZnO film, in comparison to ZnO film on quartz. We found that plasmon in Pt are responsible to provide transferred electron for electronic blocking of exciton in ZnO film induce by spontaneous recombination from Pt. In the case of Cu doped ZnO film, we confirm screening effects on exciton and a localized interband transition for both systems (ZnO film on Pt and ZnO film on quartz). In Cu-doped ZnO film, electronic blocking of exciton by Pt plasmon is more pronounce rather than screening effect by interband transition. Our results show the importance of plasmon from substrate and doping to modify the optical properties of wide bandgap semiconductor.

The ferromagnetic properties of Ta-doped and (Ta,Fe)-doped anatase TiO2 as diluted ferromagnetic materials has been studied within spin-polarized generalized gradient approximation (GGA) and GGA + U method. We observed a ferromagnetic properties in Ta- doped anatase TiO2, with a total magnetic moment of 1.00 μ B /supercell, which mainly arised due to Ti 3d and O 2p states upon Ef. Furthermore, the enhancement of ferromagnetism, mainly arising due to Fe 3d states, in (Ta,Fe)-doped anatase TiO2 was observed up to 5.00 μB /supercell, 5 times larger than that in Ta-doped TiO2. Our results confirmed the important role of Fe doping for the ferromagnetism enhancement in Ta-doped anatase TiO2.

We study the annealing effect of highly oriented zinc oxide (ZnO) films grown by low-power dc-unbalanced magnetron sputtering (DC-UBMS). In this study, we compare the structural and electrical properties of thermal-annealed ZnO films (ann-ZnO) and as-growth ZnO films (ag-ZnO) by using x-ray diffraction (XRD), scanning electron microscopy (SEM) and RT66A standardized ferroelectric test system. We found that the ag-ZnO films and the ann-ZnO films show a high orientation in (101) plane. SEM images indicate that annealing treatment at 600°C in nitrogen ambient promote the surface atomics arrangement and convert a non-uniform ag-ZnO surface to relatively flat ann-ZnO film surface. Also confirm that the ag- ZnO and the ann-ZnO films have strong ferroelectric characteristics, while the values of remnant polarization and polarization saturation are almost similar. The electric coercivity (Ec ) of the ann-ZnO film is larger than ag-ZnO films as an indication of structural defects elimination. Our results are beneficial for high energy electric-based storage devices with less depolarized structural systems.