From kesterite 2D nanosheets to wurtzite 1D nanorods:controllable synthesis of Cu-Zn-Sn-S and their application in electrocatalytic hydrogen evolution

As typical quarternary copper-based chalcogenides,Cu–Zn–Sn–S nanocrystals(CZTS NCs)have emerged as a newfashioned electrocatalyst in hydrogen evolution reactions(HERs).Oleylamine(OM),a reducing surfactant and solvent,plays a significant role in the assisting synthesis of CZTS NCs due to the ligand effect.Herein,we adopted a facile one-pot colloidal method for achieving the structure evolution of CZTS NCs from 2D nanosheets to 1D nanorods assisted through the continuous addition of OM.During the process,the mechanism of OM-induced morphology evolution was further discussed.When merely adding pure 1-dodecanethiol(DDT)as the solvent,the CZTS nanosheets were obtained.As OM was gradually added to the reaction,the CZTS NCs began to grow along the sides of the nanosheets and gradually shrink at the top,followed by the formation of stable nanorods.In acidic electrolytic conditions,the CZTS NCs with 1.0 OM addition display the optimal HER activity with a low overpotential of 561 m V at 10 m A/cm^(2) and a small Tafel slope of 157.6 m V/dec compared with other CZTS samples.The enhancement of HER activity could be attributed to the contribution of the synergistic effect of the diverse crystal facets to the reaction.

The“mediated molecular”-assisted construction of Mo_(2)N islands dispersed on Co-based nanosheets for high-efficient electrocatalytic hydrogen evolution reaction

The rational design of the catalysts with easily-accessible surface and high intrinsic activity is desirable for electrocatalytic hydrogen evolution reaction(HER).Here,we reported the construction of two-dimensional(2D)Co-Mo nitrides based heterojunctional catalyst for efficient HER based on a“mediated molecular”assisted route.The 2D Co(OH)_(2)sheet reacted partially with the“mediated molecular”(2-methylimidazole(2-MIM))to form zeolitic imidazolate framework(ZIF)-67 at surface,giving ZIF-67/Co(OH)_(2)sheets.The ZIF-67 combines with[PMo_(12)O_(40)]^(3−)cluster(PMo_(12))due to the interaction of mediated molecular with PMo_(12),producing 2D Mo-Co-2MIM/Co(OH)_(2)bimetallic precursor.After controlled nitriding,the Mo_(2)N islands dispersed on 2D porous Co-based sheets were formed.A series of characterizations and density functional theory(DFT)calculation indicated the formation of a close contact interface,which promotes the electron transfer between Mo and Co components,enhances the electron migration/redistribution and redistribution and down-shift of d-band center and thus gives a high intrinsic activity.The 2D characteristics make the catalyst more accessible contact sites,which is favourable to promot the HER.The tests showed that the optimized catalyst exhibits an onset potential of 0 mV and an overpotential of 10 mA·cm^(−2)at 35.0 mV,which is quite close to that of Pt/C catalyst.It also exhibits an activity superior to Pt/C at high current density(>100 mA·cm^(−2)).A good stability of the catalyst was achieved with no significant decay for 100 h of continuous operation.The electrolytic cell composed of optimized catalyst and P-NiFe-layered double hydroxide(LDH)can be driven by low voltage(only 1.47 V)to reach a current density of 10 mA·cm^(−2).

Synthesis of amorphous Pd-based nanocatalysts for efficient alcoholysis of styrene oxide and electrochemical hydrogen evolution

Amorphous nanomaterials with long-range disordered structures could possess distinct properties and promising applications,especially in catalysis,as compared with their conventional crystalline counterparts.It is imperative to achieve the controlled preparation of amorphous noble metal-based nanomaterials for the exploration of their phase-dependent applications.Here,we report a facile wet-chemical reduction strategy to synthesize various amorphous multimetallic Pd-based nanomaterials,including PdRu,PdRh,and PdRuRh.The phase-dependent catalytic performances of distinct Pd-based nanomaterials towards diverse catalytic applications have been demonstrated.Specifically,the usage of PdRu nanocatalysts with amorphous and crystalline face-centered cubic(fcc)phases can efficiently switch the ring-opening route of styrene oxide to obtain different products with high selectivity through alcoholysis reaction and hydrogenation reaction,respectively.Moreover,when used as an electrocatalyst for hydrogen evolution reaction(HER),the synthesized amorphous PdRh nanocatalyst exhibits low overpotential and high turnover frequency values,outperforming its crystalline fcc counterpart and most of the reported Pd-based HER electrocatalysts.

Engineering heterostructure and crystallinity of Ru/RuS_(2) nanoparticle composited with N-doped graphene as electrocatalysts for alkaline hydrogen evolution

Crystalline engineering and heterostructure have attracted much attention as effective strategies to improve the electrocatalytic activity for hydrogen evolution reaction(HER).In this study,a new heterostructure catalyst(Ru/RuS_(2)@N-rGO)with low crystallinity was fabricated by a simple and low-temperature method for HER in alkaline solution,applying the Na_(2)SO_(4)as S source and polypyrrole as N source.Optimizing through the controllable crystalline engineering and composition ratio of Ru and RuS_(2),the Ru/RuS_(2)@N-rGO heterocatalyst at the calcining 500°C revealed highly efficient HER activity with overpotential 18 mV at a current density 10 mA/cm^(2)and remarkable stability for 24 h in 1.0 mol/L KOH.This work provides a facile and effective method in designing advanced electrocatalysts for HER in the alkaline electrolytes by synergistically structural and component modulations.

纳米针尖状质子化聚苯胺负载的单原子铂催化剂实现高效酸性电解水制氢

开发高性能单原子铂催化剂对酸性电解水制氢领域具有重要意义.在酸性电解液中,氢离子(H^(+))会被水分子包围并形成水合氢离子,这会导致单原子铂活性位点的局部H^(+)浓度降低,从而使其析氢反应动力学受到限制.本研究通过将单原子铂负载在纳米针尖状质子化聚苯胺上,它既能捕获水合氢离子中的H^(+),又能通过促进电荷积累以加快H^(+)的电化学还原,从而提高单原子铂的析氢反应动力学.结果表明,相比于扁平状质子化聚苯胺负载的单原子铂,针尖状质子化聚苯胺负载的单原子铂的析氢反应转换频率得到显著提高.结合X射线光电子能谱、有限元模拟和电化学行为研究,我们发现局部H^(+)富集促使的氢溢流现象对提升纳米针尖状质子化聚苯胺负载的单原子铂催化剂的析氢活性具有重要贡献.

具有多触点界面的CoP-WP/rGO异质结助力宽pH析氢

界面工程是一种通过调整电子结构提高催化活性的有效手段.然而,构建具有紧密接触界面的异质结仍然面临巨大的挑战.本研究工作中,我们引入具有确定结构的多酸基多核钴分子团簇Co_(8)W_(18)作为前驱体,构建了紧密接触的多重界面耦合的Co P-WP异质结.通过在氧化石墨烯上生长Co_(8)W_(18),磷化处理后获得了锚定在还原氧化石墨烯上的Co P-WP异质结(Co P-WP/r GO). Co_(8)W_(18)中固有的{Co-O-W}配位模式有利于形成紧密接触的界面. X射线光电子能谱分析和理论计算证实了Co P-WP异质结中丰富的紧密接触界面促进了电子从WP向Co P的转移,从而调节了界面电子结构,优化了氢吸附自由能(ΔGH*).与氧化石墨的复合使得Co P-WP/r GO具有大的表面积和高的电导性,有利于物质传输和电荷转移.因此, Co P-WP/r GO在碱性、酸性和中性介质中皆表现出显著增强的HER活性,在10 m A cm^(-2)下过电位分别为96、130和138 m V.这项工作为设计具有多触点界面的异质结材料用作低成本和高效HER电催化剂提供了一种新策略.