4:00pm - 4:30pmKeynote
Sub-1nm Ultrathin Nanocrystals as Efficient Electrocatalysts
Tsinghua University, China
When their sizes approach near 1nm, the surface atoms in ultrathin nanostructures will become dominant as compared with those in bulk or traditional nanocrystals with bigger sizes. As a result, the influence of surface effects on the inherent properties of the whole structure will become more remarkable. In this talk, we will present the synthesis of ultrathin nanocrystals and show their applications as efficient electrocatalysts for HER, OER and ORR. A synthetic methodology for ultrathin multimetallic nanosheets was first developed to prepare Pt-Cu, Pt-Cu based sandwich, Pt-Cu-Bi-Mn and Pt-Ag-Bi-Co nanosheets, etc, which showed enhanced catalytic performances as electrocatalysts for fuel cells. Heteronanostructures including Ni-Co complex/1T MoS2 and Au-Ni nanocrystals were also constructed to show multifunctional catalytic properties for full water splitting.
 Li, H. –Y.; Chen, S. –M.; Jia, X.-F.; Song, L.; Wang, X. Nature Commun. 2017, in revision.
 Ni, B; Wang X. Chem. Sci. 2016, 7, 3978.
 Liu H. -L.; Nosheen, F.; Wang X. Chem. Soc. Rev. 2015, 44, 3056.
 Ud din, M. –A.; Saleem, F.; Wang X. Adv. Mater. 2017, adma.201604994, online.
 Saleem, F.; Xu, B.; Wang X. Adv. Mater. 2015, 27, 2013.
 Saleem, F.; Zhang, Z. –C.;Wang X. J. Am. Chem. Soc. 2013, 135, 18304.
4:30pm - 4:45pmOral
Hierarchical Metal Chalcogenides as Efficient Electrocatalysts for Hydrogen Production
Daegu Gyeongbuk Institute of Science and Technology (DGIST), South Korea
In this presentation, I will describe our recent research activities on the development of highly efficient materials for energy storage applications (water electrolysis). The noble metals are the most active in catalyzing the water electrolysis to produce pure hydrogen, but the high cost and elemental scarcity greatly hinder their widespread applications. The development of low-cost, efficient, and robust electrocatalysts (both oxygen evolution (OER) and hydrogen evolution (HER) catalysts) for water splitting is a crucial step toward the conversion and storage of sustainable energy resources such as solar energy. We have investigated the inexpensive synthesis of depositing the metal sulfides (MSx) on nickel foam for the highly efficient bi-functional water splitting to meet the current demand [1-3]. Metal sulfide on nickel foam shows the low overpotentials for OER and HER. This bi-functional catalyst is also showing robust durability about 200 h. The MSx/NF catalyst for large scale with highly efficient and durable bi-functional catalyst for water splitting outperform the noble metals such as IrO2, RuO2 electrocatalysts.
 S. Shanmugam et al. Appl.Catal. B. 203 (2017) 485.
 S. Shanmugam et al. J. Mater. Chem. A 4(2016) 16394.
 S. Shanmugam et al. Adv. Funct. Mater. 26 (2016) 4661.
4:45pm - 5:00pmOral
2D Molybdenum Carbide (MXene) as an Active Hydrogen Evolution Electrocatalyst
Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore
Active and low-cost electrocatalysts are needed to increase the kinetics of the hydrogen evolution reaction. In this talk, we present for the first time, 2D molybdenum carbide (MXene) as an efficient, non-precious metal electrocatalyst for hydrogen evolution, achieving a geometric current density of 10 mA/cm2 at an overpotential of 190 mV. The electrocatalyst also exhibits good long-term stability in acid over 1000 accelerated cyclic voltammetry cycles. Theoretical calculations based on density functional theory suggest that the basal planes of molybdenum carbide (MXene) are catalytically active, unlike in the case of widely explored molybdenum disulfide (2H-phase). This is supported by experiments performed on delaminated molybdenum carbide, which shows higher catalytic activity compared to its multilayer counterpart. This work provides insight towards the development of promising 2D materials with active basal planes which can be applied in other electrocatalytic energy conversion reactions.
5:00pm - 5:15pmOral
Preparation of 2D Nanoscale Porous Metal Oxide
Hanyang University, South Korea
2D nanoscale metal oxides have brought an abundant research interest due to their unique properties. Their intrinsic properties include high surface area, directed and fast charge transport, large aspect ratio, and controlled self-assembly all originating from their 2D morphology. Many different methods, such as ball-milled mechanical cleavage, introduction of chemical functionalities, and sonication assisted direct separation have been applied to manufacture individually isolated metal oxide sheets. However, these approaches can only be utilized on stacked-layered materials, because manufacturing 2D metal oxide using sol-gel process is too unstable to occur naturally. it is important to note that most metal oxides do not exist in stacked-layer form, but rather in non-layered bulk conformation. Therefore, tailor-made nanostructured 2D nanomaterials have not been achieved yet.
Here, a facile synthetic approach to prepare graphene-mimicking 2D metal oxide is presented. We fabricate porous 2D Co3O4 nanofoils using graphene oxide (GO) as a sacrificial template. The thermal unstability of graphene oxide and additional catalytic degradation ability of Co3O4 against carbon backbone, concede the assembly of porous 2D Co3O4 nanofoils without the loss of the 2D nature of GO. Based on these results, graphene-mimicking is suggested as a strategy to form large-area 2D transition metal oxides for application in electrochemical energy storage devices. As a proof of concept, it is demonstrated that graphene-like, porous 2D Co3O4 nanofoils exhibit a high reversible capacity (1279.2 mAh g−1), even after 50 cycles. This capacity is far beyond the theoretical capacity of Co3O4 based on the conversion mechanism from Co3O4 to Li2O and metallic Co.
5:15pm - 5:45pmInvited
Interface Engineering in Inorganic Hybrid Structures towards Improved Photocatalysis
University of Science and Technology of China, China
Designing new photocatalytic materials for improving photoconversion efficiency is a promising route to alleviate the steadily worsening environmental issues and energy crisis. Despite the invention of a large number of catalytic materials with well-defined structures, their overall efficiency in photocatalysis is still quite limited as the three key steps - light harvesting, charge generation and separation, and charge transfer to surface for redox reactions - have not been substantially improved. To improve each step in the complex process, there is a major trend to develop materials based on inorganic hybrid structures. In this case, interface engineering holds the promise for boosting the overall efficiency, given the key roles of interface structures in charge and energy transfer. In this talk, I will demonstrate several different approaches to designing inorganic hybrid structures with improved photocatalytic performance via interface engineering. The typical demonstrations include semiconductor-plasmonics systems for broad-spectrum light harvesting, metal-semiconductor interfaces for improved charge separation, semiconductor-MOF (metal-organic framework) configurations for activated surface reactions. It is anticipated that this series of works open a new window to rationally designing inorganic hybrid materials for photo-induced applications.
 Bai, S.; Yang, L.; Wang, C.; Lin, Y.; Lu, J.; Jiang, J. and Xiong, Y.*, Angew. Chem. Int. Ed. 54, 14810-14814 (2015).
 Bai, S.; Jiang, J.; Zhang, Q. and Xiong, Y.*, Chem. Soc. Rev. 44, 2893-2939 (2015).
 Bai, S.; Li, X.; Kong, Q.; Long, R.; Wang, C.; Jiang, J. and Xiong, Y.*, Adv. Mater. 27, 3444-3452 (2015).
 Bai, S.; Ge, J.; Wang, L.; Gong, M.; Deng, M.; Kong, Q.; Song, L.; Jiang, J.;* Zhang, Q.;* Luo, Y.; Xie, Y. and Xiong, Y.*, Adv. Mater. 26, 5689-5695 (2014).
 Li, R.; Hu, J.; Deng, M.; Wang, H.; Wang, X.; Hu, Y.; Jiang, H. L.; Jiang, J.;* Zhang, Q.;* Xie, Y. and Xiong, Y.*, Adv. Mater. 26, 4783-4788 (2014).
5:45pm - 6:15pmInvited
From PEC to PV Electrolysis: The Way Ahead for Solar Water Splitting
Laboratory of Photonics and Interfaces, École Polytechnique Fédérale de Lausanne, Switzerland
Solar driven water splitting has been investigated for more than four decades. However, until today there is still no commercially available large-scale device. In this talk, three types of water splitting devices ranging from conventional photoelectrochemical (PEC) approach, photovoltaic (PV) biased PEC approach, to PV electrolysis will be presented and discussed.
Despite improved understanding and control over decades of research, classical PEC photoelectrodes relying on the semiconductor and electrolyte interface are still insufficient for efficient water splitting. In addition, device stability remains an issue for most materials due to photoelectrochemical corrosion. In PV-biased PEC approach, the insufficient photovoltage is compensated by a PV cell. Thus, relative high efficiency solar water splitting was realized. Later on, inspired by photovoltaic field, p-n junction concept was used to form buried junctions for modern photoelectrodes. Concurrently, approaches were developed to stabilize materials which themselves are unstable in water splitting conditions through overlayer protection. Now a modern photoelectrode consists of selective contact, photoabsorber, p-n junction, protection layer and catalyst overlayer. Strictly speaking, this type of photoelectrode should be categorized as PV electrolysis, as they rely on the solid state p-n junction for charge separation and water only serves as an ohmic contact.
Among PEC, PV biased PEC and PV electrolysis approaches, PV electrolysis currently takes the lead. However, it is still not clear which approach will finally make the day for hydrogen fuel economy, as none of them currently satisfices the requirements of high efficiency, long stability and low cost at the same time. Instead of focusing on only one approach, synergistic efforts combing the merits of all possible routes should be made. Both research efforts from scientists and policy supports from the public are demanded to achieve the Holy Grail of solar water splitting.