Ma Shulan of Beijing Normal University and his collaborator JACS: MoS2 / Co9S8 / Ni3S2 / Ni multi-stage nano assembly material with high efficiency and wide pH range

In recent years, the large-scale utilization of traditional fossil fuels has led to energy shortage, environmental pollution and many other problems, so it is urgent to develop clean and efficient new energy Hydrogen energy, as a clean renewable energy, has the advantages of high calorific value and water as the combustion product It is an ideal alternative fuel for traditional fossil energy Hydrogen energy can be directly obtained by electrolyzing water, which is composed of her and oer Both her and oer processes need high over potential, so appropriate electrocatalyst should be used to reduce the over potential in order to realize industrial application Up to now, the precious metals represented by Pt, IR and Ru are the best catalysts for hydrogen production from electrolyzed water However, precious metal resources are scarce, expensive and the production cost is very high, which limits its industrialization Therefore, it is an important task to explore efficient and stable electrocatalysts The existing catalysts usually only have high catalytic activity for one reaction (oer or her), so two different types of catalysts are needed for the electrolytic water reaction This makes the equipment of electrolyzing water more complex and increases the operating cost The above problems can be effectively solved by assembling the catalysts with different functions into a composite material and constructing a dual-function catalyst for total water removal In addition, most of the reported total solution water is carried out under alkaline condition Compared with alkali, electrolyzed water under acid condition has the advantages of simplicity and higher current density However, strong acid and strong alkali conditions require high equipment and are harmful to the environment In the long run, electrolyzed water (such as sea water or river water) under neutral conditions is a better choice Therefore, it is a very challenging work to design a low-cost, high-efficiency and wide pH range dual functional electrocatalyst with both her and oer catalytic activities MoS 2 has better her catalytic activity, and it is easy to get the researchers' attention because of its low price, but its oer catalytic performance is poor; CO 9s 8 has excellent oer catalytic performance, but its her performance needs to be improved In this work, the interaction of MoS 2 and Co 9 S 8 nanosheets was designed and applied to Ni 3 S 2 nanorod arrays, which were loaded on three-dimensional foam nickel (NF) to form multistage co assembly materials The material has good conductivity and can be used as electrode directly By adjusting the molar ratio of CO: Mo precursor, the morphology and composition of comonis NF X Y composite (X: y is the molar ratio of CO: Mo, 5:1 ~ 1:3) can be controlled Comonis-nf-31 showed the best electrocatalytic activity In alkaline, acidic and neutral electrolytes, it could reach a current density of 10 Ma cm-2 at ultra-low over potential (113, 103 and 117 MV, her) and (166, 228 and 405 MV, OER) Based on the excellent performance of her and oer of comonis-nf-31, a double electrode electrolytic cell was assembled and the cell voltage of 10 Ma cm-2 current density was 1.54, 1.45 and 1.80 V in alkaline, acid and neutral medium Theoretical calculation shows that the high oer activity of the material is due to the electron transfer from CO 9s 8 to MoS 2 at the interface, which changes the binding energy of the adsorbed material and reduces the overpotential This work is the first report of metal sulfides in the full pH electrocatalytic hydrolysis of water, which provides an important idea for the design and development of high-efficiency and low-cost bifunctional catalyst for hydrogen production from electrolyzed water Professor Ma Shulan, School of chemistry, Beijing Normal University, cooperated with Professor Mercouri g kanatzidis, Northwestern University, and Professor Peter Zapol, Argonne National Laboratory of the United States, to make the research achievements as a high efficient wide pH range electrocatalytic system for overall water "Splitting", published in J am Chem SOC (DOI: 10.1021 / JACS 9b04492) Beijing Normal University is the first completion unit, and Yang Yan, Ph.D student, School of chemistry, Beijing Normal University, is the first author.