Patterned Synthesis of Pd₄S: Chemically Robust Electrodes and Conducting Etch Masks

Abstract

A simple, one‐step process to synthesize Pd4S films is reported here along with their characterization using X‐ray diffraction, electron microscopy, and electrical measurements. The synthesis involves thermolysis of a single‐source precursor, namely palladium alkanethiolate, in H2 atmosphere at 250 °C for 3 h. The films are highly conducting and resistant to strong acidic, alkali, and oxidizing environments. The precursor allows patterning of the Pd4S films by electron beam lithography and micromolding, an attribute that has been employed in making chemically resistant electrodes and etch masks. The conversion of palladium thiolate to other sulfide phases is also achieved.

Evolution of palladium sulfide phases during thermal treatments and consequences for acetylene hydrogenation

“…However, it was worth noting that the phase composition gradually shifted from a palladium-lean PdS phase to a palladium-rich Pd4S phase (Table 2), and the oxidation state of Pd changed from positive to a near neutral charge ( Figure 6 and 7) with an increase in the reduction temperature, which was similar with the properties of Pd metal/alloy. [58] Based on the above results, it is believed that sample reduced at 350ºC possesses a greater ability to activate hydrogen than R50, R150 and R250 due to this metallic characteristic [47,69] and consequently contributed to the enhanced activity.…”

“…However, given that palladium sulfides are known to be permeable to hydrogen, [69,70] it seems more likely that hydrogen diffuses from the surface into the bulk to find a S atom. That being the case, one would expect that sulfur atoms are abstracted from surface and near surface sites first.…”

Micromolding—A Soft Lithography Technique

“…Patterned Pd microstripes [26] (Figure 16.7) were formed by Kulkarni and coworkers on diverse substrates including flexible substrates using Pd thiolate as ink for molding [29]. Not only Pd metal but also Pd sulfides such as Pd 4 S, Pd 16 S 7 , and PdS could be produced from the same precursor by thermolyzing it in a controlled atmosphere such as H 2 [30]. Thus, molded patterns of Pd 4 S have been realized [30], which may be useful as corrosion-resistant and gas-impermeable conduits, owing to the known properties of Pd 4 S. In a similar manner, using a solution of Pt-carbonyl clusters, Greco et al [31] have obtained conductive molecular wires of submicrometer width by micromolding ( Figure 16.8a-c).…”

“…Not only Pd metal but also Pd sulfides such as Pd 4 S, Pd 16 S 7 , and PdS could be produced from the same precursor by thermolyzing it in a controlled atmosphere such as H 2 [30]. Thus, molded patterns of Pd 4 S have been realized [30], which may be useful as corrosion-resistant and gas-impermeable conduits, owing to the known properties of Pd 4 S. In a similar manner, using a solution of Pt-carbonyl clusters, Greco et al [31] have obtained conductive molecular wires of submicrometer width by micromolding ( Figure 16.8a-c). On thermal annealing, decomposition of the precursor leads to the formation of metallic Pt, with conductivity increasing by two orders of magnitude.…”

Reactivity of 4‐Pyridyltellurolate with Pd(II)/Pt(II) Complexes

“…The Pd(II) complexes of sulfur and selenium based chalcogenoether and chalcogenolate ligands have emerged as highly efficient homogeneous catalysts for C−C bond forming reactions such as Suzuki and Heck reactions. The thiolates/selenolates of M(II) (M=Pd, Pt) have been used as molecular precursors for the synthesis of metal/metal‐enriched chalcogenides such as ME, Pd 4 E, (E=S, Se), Pd 17 Se 15 , etc which have largely been used as catalysts, semiconducting materials and electrodes. The coordination chemistry of sulfur ligands is well developed due to the diversified applications starting from biology to nanomaterials.…”