Fast Motion Planning of UAVs

Fast motion planning (FMP) of autonomous vehicles has been advanced rapidly for robotics research, particularly for trajectory planning of spacecraft. The FMP team at JPL and Caltech has developed an algorithm for autonomous vehicles in environments with many fixed obstacles. The spherical expansion and sequential convex programming (SE-SCP) algorithm is computationally efficient and guarantees any-time local optimality for a given function on top of being faster than other sampling-based motion planning methods. Spherical Expansion (SE) is randomized sampling to explore the workspace of the autonomous vehicle and it finds an initial cost-minimized path. Sequential convex programming (SCP) then optimizes this path and computes a locally optimal trajectory. Current development and simulation of the SE-SCP algorithm is still being tested with MATLAB software as well as the collaborative robotics software called the Robot Operating System (ROS). ROS has advantages over MATLAB since it is a flexible framework for writing robotics software and includes a collection of tools, libraries, and conventions specifically for robotics improvement. By developing a SE-SCP simulation in ROS, a ROS package can be created and uploaded online, which provides opportunities for the public to easily utilize the software and apply the SE-SCP algorithm for motion planning to their own autonomous vehicles

FINANCING GREEN: REFORMING GREEN BOND REGULATION IN THE UNITED STATES

In recent years, green bonds have emerged as a way for the financial industry to contribute to environmentally friendly projects, combat climate change, and provide funds for green infrastructures across the world. While the green bond market has expanded drastically across large nations in Europe and Asia, market growth has stalled in the United States, in part due to a lack of promising regulations in the United States. Existing regulations on green bond issuance in the United States only exists in the form of non-binding international guidelines. This Note reviews the benefits and potentials of green bonds both as an investment tool and a tool for green growth, through the lens of existing international and domestic guidelines. This Note argues that for the green bond market to further expand in the United States, mandatory regulatory support must be imposed on bond issuers through the use of a tiered green bond system, mandated quarterly reports by bond issuers to investors, and imposition of stricter penalties for issuers who misuse the bond money

Recent progress in metal–organic framework/graphene-derived materials for energy storage and conversion: design, preparation, and application

Graphene or chemically modified graphene, because of its high specific surface area and abundant functional groups, provides an ideal template for the controllable growth of metal–organic framework (MOF) particles. The nanocomposite assembled from graphene and MOFs can effectively overcome the limitations of low stability and poor conductivity of MOFs, greatly widening their application in the field of electrochemistry. Furthermore, it can also be utilized as a versatile precursor due to the tunable structure and composition for various derivatives with sophisticated structures, showing their unique advantages and great potential in many applications, especially energy storage and conversion. Therefore, the related studies have been becoming a hot research topic and have achieved great progress. This review summarizes comprehensively the latest methods of synthesizing MOFs/graphene and their derivatives, and their application in energy storage and conversion with a detailed analysis of the structure–property relationship. Additionally, the current challenges and opportunities in this field will be discussed with an outlook also provide

Synergistically boosting the elementary reactions over multiheterogeneous ordered macroporous Mo2C/NC-Ru for highly efficient alkaline hydrogen evolution

Simultaneously enhancing the reaction kinetics, mass transport, and gas release during alkaline hydrogen evolution reaction (HER) is critical to minimizing the reaction polarization resistance, but remains a big challenge. Through rational design of a hierarchical multiheterogeneous three-dimensionally (3D) ordered macroporous Mo2C-embedded nitrogen-doped carbon with ultrafine Ru nanoclusters anchored on its surface (OMS Mo2C/NC-Ru), we realize both electronic and morphologic engineering of the catalyst to maximize the electrocatalysis performance. The formed Ru-NC heterostructure shows regulative electronic states and optimized adsorption energy with the intermediate H*, and the Mo2C-NC heterostructure accelerates the Volmer reaction due to the strong water dissociation ability as confirmed by theoretical calculations. Consequently, superior HER activity in alkaline solution with an extremely low overpotential of 15.5 mV at 10 mA cm−2 with the mass activity more than 17 times higher than that of the benchmark Pt/C, an ultrasmall Tafel slope of 22.7 mV dec−1, and excellent electrocatalytic durability were achieved, attributing to the enhanced mass transport and favorable gas release process endowed from the unique OMS Mo2C/NC-Ru structure. By oxidizing OMS Mo2C/NC-Ru into OMS MoO3-RuO2 catalyst, it can also be applied as efficient oxygen evolution electrocatalyst, enabling the construction of a quasi-symmetric electrolyzer for overall water splitting. Such a device's performance surpassed the state-of-the-art Pt/C || RuO2 electrolyzer. This study provides instructive guidance for designing 3D-ordered macroporous multicomponent catalysts for efficient catalytic applications

Dense platinum/nickel oxide heterointerfaces with abundant oxygen vacancies enable ampere-level current density ultrastable hydrogen evolution in alkaline

Platinum (Pt) remains the benchmark electrocatalyst for alkaline hydrogen evolution reaction (HER), but its industry-scale hydrogen production is severely hampered by the lack of well-designed durable Pt-based materials that can operate at ampere-level current densities. Herein, based on the original oxide layer and parallel convex structure on the surface of nickel foam (NF), a 3D quasi-parallel architecture consisting of dense Pt nanoparticles (NPs) immobilized oxygen vacancy-rich NiOx heterojunctions (Pt/NiOx-OV) as an alkaline HER catalyst is developed. A combined experimental and theoretical studies manifest that anchoring Pt NPs on NiOx-OV leads to electron-rich Pt species with altered density of states (DOS) distribution, which can efficiently optimize the d-band center and the adsorption of reaction intermediates as well as enhance the water dissociation ability. The as-prepared catalyst exhibits extraordinary HER performance with a low overpotential of 19.4 mV at 10 mA cm−2, a mass activity 16.3-fold higher than that of 20% Pt/C, and a long durability of more than 100 h at 1000 mA cm−2. Furthermore, the assembled alkaline electrolyzer combined with NiFe-layered double hydroxide requires extremely low voltage of 1.776 V to attain 1000 mA cm−2, and can operate stably for more than 400 h, which is rarely achieved

Zinc-doping strategy on P2-type Mn-based layered oxide cathode for high-performance potassium-ion batteries

Mn-based layered oxide is extensively investigated as a promising cathode material for potassium-ion batteries due to its high theoretical capacity and natural abundance of manganese. However, the Jahn–Teller distortion caused by high-spin Mn3+(t2g3eg1) destabilizes the host structure and reduces the cycling stability. Here, K0.02Na0.55Mn0.70Ni0.25Zn0.05O2 (denoted as KNMNO-Z) is reported to inhibit the Jahn–Teller effect and reduce the irreversible phase transition. Through the implementation of a Zn-doping strategy, higher Mn valence is achieved in the KNMNO-Z electrode, resulting in a reduction of Mn3+ amount and subsequently leading to an improvement in cyclic stability. Specifically, after 1000 cycles, a high retention rate of 97% is observed. Density functional theory calculations reveals that low-valence Zn2+ ions substituting the transition metal position of Mn regulated the electronic structure around the Mn-O bonding, thereby alleviating the anisotropic coupling between oxidized O2− and Mn4+ and improving the structural stability. K0.02Na0.55Mn0.70Ni0.25Zn0.05O2 provided an initial discharge capacity of 57 mAh g−1 at 100 mA g−1 and a decay rate of only 0.003% per cycle, indicating that the Zn-doped strategy is effective for developing high-performance Mn-based layered oxide cathode materials in PIBs

Boosting the bifunctionality and durability of cobalt-fluoride-oxide nanosheets for alkaline water splitting through nitrogen-plasma-promoted electronic regulation and structural reconstruction

Designing cost-effective and durable bifunctional electrocatalysts with high activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial for large-scale hydrogen production through water splitting. However, many electrocatalysts undergo surface or bulk reconstruction, leading to an unstable catalytic activity. In this study, we present a facile N2 plasma strategy to enhance the electrocatalytic activity of cobalt-fluoride-oxide (CoFO, herein NCoFO) nanosheets while maintaining reasonably stable performance. The optimized NCoFO nanosheets grown on carbon cloth through a 60 s N2 plasma treatment (NCoFO/CC-60) exhibit remarkable performance with low overpotentials of 203 mV and 230 mV at 10 mA cm-2 for the HER and the OER, respectively. Density functional theory calculations revealed that the enhanced catalytic performance is attributed to the regulated local electronic configuration resulting from plasma treatment. Furthermore, the assembled alkaline electrolyzer NCoFO/CC-60||NCoFO/CC-60 requires an extremely low voltage of 1.48 V to attain 10 mA cm-2 for over a 150 h operation, which is superior to the values obtained for Pt/C||RuO2 (1.50 V) and CoFO/CC||CoFO/CC (1.55 V)

In situ immobilizing atomically dispersed Ru on oxygen-defective Co3O4 for efficient oxygen evolution

The synergistic regulation of the electronic structures of transition-metal oxide-based catalysts via oxygen vacancy defects and single-atom doping is efficient to boost their oxygen evolution reaction (OER) performance, which remains challenging due to complex synthetic procedures. Herein, a facile defect-induced in situ single-atom deposition strategy is developed to anchor atomically dispersed Ru single-atom onto oxygen vacancy-rich cobalt oxides (Ru/Co3O4–x) based on the spontaneous redox reaction between Ru3+ ions and nonstoichiometric Co3O4–x. Accordingly, the as-prepared Ru/Co3O4–x electrocatalyst with the coexistence of oxygen vacancies and Ru atoms exhibits excellent performances toward OER with a low overpotential of 280 mV at 10 mA cm–2, a small Tafel slope value of 86.9 mV dec–1, and good long-term stability in alkaline media. Furthermore, density functional theory calculations uncover that oxygen vacancy and atomically dispersed Ru could synergistically tailor electron decentralization and d-band center of Co atoms, further optimizing the adsorption of oxygen-based intermediates (*OH, *O, and *OOH) and reducing the reaction barriers of OER. This work proposes an available strategy for constructing electrocatalysts with abundant oxygen vacancies and atomically dispersed noble metal and presents a deep understanding of synergistic electronic engineering of transition-metal-based catalysts to boost oxygen evolution

FINANCING GREEN: REFORMING GREEN BOND REGULATION IN THE UNITED STATES

In recent years, green bonds have emerged as a way for the financial industry to contribute to environmentally friendly projects, combat climate change, and provide funds for green infrastructures across the world. While the green bond market has expanded drastically across large nations in Europe and Asia, market growth has stalled in the United States, in part due to a lack of promising regulations in the United States. Existing regulations on green bond issuance in the United States only exists in the form of non-binding international guidelines. This Note reviews the benefits and potentials of green bonds both as an investment tool and a tool for green growth, through the lens of existing international and domestic guidelines. This Note argues that for the green bond market to further expand in the United States, mandatory regulatory support must be imposed on bond issuers through the use of a tiered green bond system, mandated quarterly reports by bond issuers to investors, and imposition of stricter penalties for issuers who misuse the bond money