Electrocatalysts With Pt-similar Performance: The Design And Its Electrocatalyzing Hydrazine/Water Reactions

Hydrogen energy has been considered as the best choice for the next-generation clean energy due to its high mass-specific energy density,non-toxic product and zero-carbon emissions.Overall water splitting（OWS）system composed of two half reactions:hydrogen evolution reaction（HER）and oxygen evolution reaction（OER）,has been an important way for large-scale industrial hydrogen production because of its simple structure,abundant resources and recyclable.However,OER,along with slow kinetic rate and high overpotential,sets a hurdle for furtherly enhancing hydrogen production efficiency of OWS system.In recent years,utilizing hydrazine oxidation reaction（Hz OR）to couple with HER instead of OER to reduce water decomposition voltage,overall hydrazine splitting（OHz S）system could highly improve electrochemical hydrogen production efficiency,which has attracted widespread attention.At present,noble metal Pt has highly catalytic activity for HER and Hz OR.But owning to its expensive price,it’s imperative to develop a catalyst with near platinum activity.Therefore,two types of high efficiency catalysts with high electrocatalytic performance and efficiency for OWS and OHz S systems have been designed and investigated in this paper:（1）Firstly,（VO）₂P₂O₇ nanosheets with a two-dimensional layered structure is synthesized by a two-step method.In alkaline electrolytes,（VO）₂P₂O₇ nanosheets exhibit a very low overpotential（30 m V）at 10 m A cm^-2,which is close to the overpotential of Pt/C.Theoretical calculation results confirm the excellent intrinsic catalytic activity of（VO）₂P₂O₇ nanosheets.At the same time,（VO）₂P₂O₇ nanosheets exhibit good electrochemical stability,where is no obvious attenuation after long-term（20 h）electrocatalysis.Notable,it could also be used as a bifunctional catalyst to drive OWS system at a small working voltage of 1.51 V to obtain 10 m A cm^-2.（2）Secondly,Rh₂S₃/N-doped carbon hybrid（Rh₂S₃/NC）is synthesized and firstly applied as an efficient and stable bifunctional catalyst for OHz S over a wide p H range.Rh₂S₃/NC shows high HER and Hz OR activities in alkaline,neutral and acid electrolytes,and has excellent electrocatalytic stability（70 h）.The results of density functional theory（DFT）calculations show that Rh₂S₃/NC not only promotes the adsorption and desorption of hydrogen atoms,but also forms a more stable structure of adsorbed*NNH.In OHz S electrolyzer,Rh₂S₃/NC shows higher catalytic activity than Pt/C counterpart in whole-p H environment.And compared with the corresponding OWS,this system could save more than 93.3%,85.2% and 78.3% of energy consumption,respectively.