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Dohyung Kim, Christopher S Kley, Yifan Li, Peidong Yang
Direct conversion of carbon dioxide to multicarbon products remains as a grand challenge in electrochemical CO2 reduction. Various forms of oxidized copper have been demonstrated as electrocatalysts that still require large overpotentials. Here, we show that an ensemble of Cu nanoparticles (NPs) enables selective formation of C2-C3 products at low overpotentials. Densely packed Cu NP ensembles underwent structural transformation during electrolysis into electrocatalytically active cube-like particles intermixed with smaller nanoparticles...
September 18, 2017: Proceedings of the National Academy of Sciences of the United States of America
Bin Liu, Hui-Qing Peng, Cheuk-Nam Ho, Hongtao Xue, Shuilin Wu, Tsz-Wai Ng, Chun-Sing Lee, Wenjun Zhang
A novel mesoporous nanosheet networked hybrid comprising Co3 O4 and Co3 (PO4 )2 is successfully synthesized using a facile and scalable method through calcinating the carbon, cobalt hydroxy carbonate, and cobalt phosphate composite precursor. Electron transfer from Co3 O4 to Co3 (PO4 )2 , together with the special networked structure and the porous nature of the nanosheets enable the Co3 (PO4 )2 -Co3 O4 hybrid to have a high oxygen evolution reaction (OER) activity and outstanding stability in alkaline electrolyte, e...
September 18, 2017: Small
Lennart Köhler, Majid Ebrahimizadeh Abrishami, Vladimir Roddatis, Janis Geppert, Marcel Risch
Targeted improvement of the low efficiency of water oxidation during the oxygen evolution reaction (OER) is severely hindered by insufficient knowledge of the electrocatalytic mechanism on heterogeneous surfaces. We chose LiMn2O4 as a model system for mechanistic investigations as it shares the cubane structure with the active site of photosystem II and the valence of Mn3.5+ with the dark-stable S1 state in the mechanism of natural photosynthesis. The investigated LiMn2O4 nanoparticles are electrochemically stable in NaOH electrolytes and show respectable activity in any of the main metrics...
September 18, 2017: ChemSusChem
Yanming Liu, Yujing Zhang, Kai Chen, Xie Quan, Xinfei Fan, Yan Su, Shuo Chen, Huimin Zhao, Yaobin Zhang, Hongtao Yu, Michael R Hoffmann
Electrochemical reduction of CO2 to ethanol, a clean and renewable liquid fuel with high heating value, is an attractive strategy for global warming mitigation and resource utilization. However, converting CO2 to ethanol remains great challenge due to the low activity, poor product selectivity and stability of electrocatalysts. Here, B and N codoped nanodiamond (BND) was reported as an efficient and stable electrode for selective reduction of CO2 to ethanol. Good ethanol selectivity was achieved on BND with high Faradaic efficiency of 93...
September 15, 2017: Angewandte Chemie
Hanguang Zhang, Sooyeon Hwang, Maoyu Wang, Zhenxing Feng, Stavros Karakalos, Langli Luo, Zhi Qiao, Xiaohong Xie, Chongmin Wang, Dong Su, Yuyan Shao, Gang Wu
It remains a grand challenge to replace platinum group metal (PGM) catalysts with earth abundant materials for the oxygen reduction reaction (ORR) in acidic media, which is crucial for large-scale deployment of proton exchange membrane fuel cells (PEMFCs). Here, we report a high-performance atomic Fe catalyst derived from chemically Fe-doped zeolitic imidazo-late frameworks (ZIFs) by directly bonding Fe ions to imidazolate ligands within 3D frameworks. Although the ZIF was iden-tified as a promising precursor, the new synthetic chemistry enables well-dispersed atomic Fe sites embedded into porous carbon without the formation of aggregates...
September 13, 2017: Journal of the American Chemical Society
Yanlong Lv, Liu Yang, Dapeng Cao
The severe dependence of oxygen reduction reaction (ORR) in fuel cells on platinum (Pt)-based catalysts greatly limits the process of their commercialization. Therefore, developing cost-reasonable non-precious-metal catalysts to replace Pt-based catalysts for ORR is an urgent task. Here, we use the composite of inexpensive polyaniline and superfine polytetrafluoroethylene powder as precursor to synthesize a metal-free N,F-codoped porous carbon catalyst (N,F-Carbon). Results indicate that the N,F-Carbon catalyst obtained at the optimized temperature 1000 °C exhibits almost the same onset (0...
September 18, 2017: ACS Applied Materials & Interfaces
Bing Zhang, Shu-Yu Zhao, Hong-Hui Wang, Tian-Jian Zhao, Yong-Xing Liu, Li-Bing Lv, Xiao Wei, Xin-Hao Li, Jie-Sheng Chen
The oxygen evolution reaction (OER) is the rate-limiting process for water splitting, and highly efficient large-area OER photoanodes have been considered as an essential part in photoelectrochemical water splitting reactors. The high hole-electron separation efficiency of photoanodes is highly required for real applications of photoanodes in sufficiently harvesting solar energy. Herein we show that the inactive g-C3N4 nanolayers can be self-assembled with BiVO4 into a highly coupled BV/CN dyad to significantly enhance the charge separation efficiency of BiVO4 photoelectrodes for the OER...
September 11, 2017: Chemical Communications: Chem Comm
Yun Huang, Yilin Deng, Albertus Denny Handoko, Gregory K L Goh, Boon Siang Yeo
The selective electroreduction of CO2 to formate (or formic acid) is currently of great interest in the field of renewable energy utilization. In this work, we designed a sulfur-doped Cu2O-derived Cu catalyst, and showed that the presence of sulfur could significantly tune the selectivity of Cu from producing a myriad of CO2 reduction products to almost exclusively formate. Sulfur is doped into the Cu catalysts by dipping the Cu substrates into ammonium polysulfide solutions. Catalyst films with the highest sulfur content of 2...
September 7, 2017: ChemSusChem
Nathalie Minko Ito, Waldemir Moura Carvalho, Dereck Nills Ferreira Muche, Ricardo Hauch Ribeiro Castro, Gustavo Martini Dalpian, Flavio Leandro Souza
Here we show that chlorine species originating from commonly used iron precursors annihilate the hematite nanorod photocurrent by providing recombination pathways. Although hematite nanorod films could be obtained by thermal decomposition of the iron oxyhydroxide phase (β-FeOOH), indistinguishable photocurrent responses under dark and sunlight irradiation conditions were observed until the nanorods were annealed (activated) at 750 °C. The annealing led to the elimination of observable chlorine species and allowed photocurrent responses of 1...
September 6, 2017: Physical Chemistry Chemical Physics: PCCP
Wanglian Liu, John Benson, Craig Dawson, Andrew Strudwick, Arun Prakash Aranga Raju, Yisong Han, Meixian Li, Pagona Papakonstantinou
The rational design of transition metal dichalcogenide electrocatalysts for efficiently catalyzing the hydrogen evolution reaction (HER) is believed to lead to the generation of a renewable energy carrier. To this end, our work has made three main contributions. At first, we have demonstrated that exfoliation via ionic liquid assisted grinding combined with gradient centrifugation is an efficient method to exfoliate bulk WS2 to nanosheets with a thickness of a few atomic layers and lateral size dimensions in the range of 100 nm to 2 nm...
September 4, 2017: Nanoscale
Ruiyang Yin, Mingyang Liu, Rui Tang, Longwei Yin
In this work, we demonstrate a facile successive ionic layer adsorption and reaction process accompanied by hydrothermal method to synthesize CdS nanoparticle-modified α-Fe2O3/TiO2 nanorod array for efficient photoelectrochemical (PEC) water oxidation. By integrating CdS/α-Fe2O3/TiO2 ternary system, light absorption ability of the photoanode can be effectively improved with an obviously broadened optical-response to visible light region, greatly facilitates the separation of photogenerated carriers, giving rise to the enhancement of PEC water oxidation performance...
September 2, 2017: Nanoscale Research Letters
K Wippermann, J Giffin, S Kuhri, W Lehnert, C Korte
The influence of the water content of 2-sulfoethylmethylammonium trifluoromethanesulfonate [2-Sema][TfO] on the double layer properties of the interface of platinum and the proton conducting ionic liquid (PIL) is investigated by means of impedance spectroscopy and cyclic voltammetry. By fitting the impedance spectra as complex capacitances, up to four differential double layer capacitances and corresponding time constants are obtained, depending on the potential (U = 0-1.6 V/RHE), water content (0.7-6.1 wt%) and temperature (T = 70-110 °C)...
September 1, 2017: Physical Chemistry Chemical Physics: PCCP
Christopher Schneider, Ning Liu, Patrik Schmuki
Tantalum doped rutile nanorods were hydrothermally grown on FTO substrates using a new seeding approach. This approach allows the incorporation of high concentrations of up to 4.8 at% tantalum as active doping and results in a significant enhancement of the photoelectrochemical water splitting rate (1.8 mA cm(-2) at a potential of +1.5 V vs. RHE) which corresponds to ∼1% photocurrent conversion efficiency under AM 1.5, 100 mW cm(-2) simulated sunlight irradiation.
August 25, 2017: Chemical Communications: Chem Comm
John Mondal, Subhash Chnadra Shit, Santimoy Khilari, Indranil Mondal, Debabrata Pradhan
In this study, we report the design and sequential synthesis of novel cobalt sulfide nanoparticles grafted Porous Organic Polymer nanohybrid (CoSx@POP) as active and durable water-splitting Photoelectrocatalyst in hydrogen evolution reaction. The specific textural and relevant chemical properties of as-synthesized nanohybrid materials (Co3O4@POP & CoSx@POP) were investigated by means of XRD, XPS, FT-IR, 13C CP MAS NMR, HR-TEM, HAADF-STEM with the corresponding elemental mapping, FE-SEM and nitrogen physisorption studies...
August 24, 2017: Chemistry: a European Journal
Zhiliang Wang, Xu Zong, Yuying Gao, Jingfeng Han, Zhiqiang Xu, Zheng Li, Chunmei Ding, Shengyang Wang, Can Li
Photoelectrochemical water splitting provides an attractive way to store solar energy in molecular hydrogen as a kind of sustainable fuel. To achieve high solar conversion efficiency, the most stringent criteria are effective charge separation and injection in electrodes. Herein, efficient photoelectrochemical water oxidation is realized by optimizing charge separation and surface charge transfer of GaN:ZnO photoanode. The charge separation can be greatly improved through modified moisture-assisted nitridation and HCl acid treatment, by which the interfaces in GaN:ZnO solid solution particles are optimized and recombination centers existing at the interfaces are depressed in GaN:ZnO photoanode...
September 13, 2017: ACS Applied Materials & Interfaces
Shota Miyashita, Mitsuru Wakisaka, Akihiro Iiyama, Hiroyuki Uchida
We have analyzed the surface oxidation process of Pt nanoparticles that were uniformly dispersed on a glassy carbon electrode (Pt/GC), which was adopted as a model of a practical Pt/C catalyst for fuel cells, in N2-purged 0.1 M HF solution by using angle-resolved, grazing-incidence X-ray photoelectron spectroscopy combined with an electrochemical cell (EC-ARGIXPS). Positive shifts in the binding energies of Pt 4f spectra were clearly observed for the surface oxidation of Pt nanoparticles at potentials E > 0...
August 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Hyungseob Lim, Jae Young Kim, Edward J Evans, Amritesh Rai, Jun-Hyuk Kim, Bryan R Wygant, C Buddie Mullins
There has been debate on whether Ni(OH)2 is truly catalytically active for the photo/electrocatalytic oxygen evolution reaction. In this report, we synthesized a Ni(OH)2 cocatalyst on a hematite photoanode and showed that, as has been proposed in other studies, the current density varies as a function of scan rate, which arises due to a photoinduced capacitive charging effect. We discovered that this photoinduced charging of Ni(2+/3+) can be overcome by mixing cerium nitrate into the Ni precursor solution. Under illumination, the NiCeOx cocatalyst on a hematite photoanode exhibited an approximately 200 mV cathodic shift in onset potential and a ∼53% enhancement in photocurrent at 1...
September 13, 2017: ACS Applied Materials & Interfaces
Can Wu, Yuhang Zhang, Duo Dong, Haiming Xie, Jinghong Li
To promote the practical application of electrochemical energy storage and conversion systems, nonprecious electrocatalysts of low cost and with highly efficient performance in oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are highly desired. In this work, a cubic sodium chloride (NaCl) crystal-templated strategy is proposed for coupling Co9S8 nanoparticles to nitrogen- and sulfur-doped carbon nanosheets (Co9S8/N,S-CNS) by facile pyrolysis. The nitrogen and sulfur dual-doped carbon nanosheets can effectively prevent the aggregation of Co9S8 nanoparticles and greatly improve the conductivity of the hybrid structure...
August 31, 2017: Nanoscale
Seungtaeg Oh, Hakhyeon Song, Jihun Oh
Photoelectrochemical (PEC) cells have attracted much attention as a viable route for storing solar energy and producing value-added chemicals and fuels. However, the competition between light absorption and electrocatalysis at a restrained cocatalyst area on conventional planar-type photoelectrodes could limit their conversion efficiency. Here, we demonstrate a new monolithic photoelectrode architecture that eliminate the optical-electrochemical coupling by forming locally nanostructured cocatalysts on a photoelectrode...
September 13, 2017: Nano Letters
Jie Zhang, Lu Chen, Fengwang Li, Ying Zhang, Cameron Bentley, Mike Horne, Alan Bond
Electrocatalytic reduction of CO2 present in a 30% (w/w) monoethanolamine (MEA) aqueous solution has been undertaken at In, Sn, Bi, Pb, Pd, Ag, Cu and Zn metal electrodes. Upon dissolution of CO2, the non-conducting MEA solution is transformed into a conducting one, as needed for electrochemical reduction of CO2. Both an increase in the electrode surface porosity and addition of surfactant cetyltrimethylammonium bromide (CTAB) suppress the competing hydrogen evolution reaction with the latter having a significantly stronger impact...
August 10, 2017: ChemSusChem
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