Synthesis methods and applications of palladium nanoparticles: A review

Abstract

Palladium (Pd) is a key component of many catalysts. Nanoparticles (NPs) offer a larger surface area than bulk materials, and with Pd cost increasing 5-fold in the last 10 years, Pd NPs are in increasing demand. Due to novel or enhanced physicochemical properties that Pd NPs exhibit at the nanoscale, Pd NPs have a wide range of applications not only in chemical catalysis, but also for example in hydrogen sensing and storage, and in medicine in photothermal, antibacterial, and anticancer therapies. Pd NPs, on the industrial scale, are currently synthesized using various chemical and physical methods. The physical methods require energy-intensive processes that include maintaining high temperatures and/or pressure. The chemical methods usually involve harmful solvents, hazardous reducing or stabilizing agents, or produce toxic pollutants and by-products. Lately, more environmentally friendly approaches for the synthesis of Pd NPs have emerged. These new approaches are based on the use of the reducing ability of phytochemicals and other biomolecules to chemically reduce Pd ions and form NPs. In this review, we describe the common physical and chemical methods used for the synthesis of Pd NPs and compare them to the plant- and bacteria-mediated biogenic synthesis methods. As size and shape determine many of the unique properties of Pd NPs on the nanoscale, special emphasis is given to the control of these parameters, clarifying how they impact current and future applications of this exciting nanomaterial.

Application of a magnetically separable Zr-MOF for fast extraction of palladium before its spectrophotometric detection

“…It is also utilized in many electrical devices as a substitute for gold in galvanic components because of its high stability and excellent conductivity. It is also employed in anti-cancer pharmaceuticals [ 1 ]. Pd is applied in the process of creating nitric acid and petroleum in the chemical industry.…”

One-pot green bio-assisted synthesis of highly active catalytic palladium nanoparticles in porcine gastric mucin for environmental applications

“…17 Among all the methods, chemical reduction and encapsulation of PdNPs are considered relatively simple and reproducible, resulting in the homogeneous formation of PdNPs in terms of shape and size. [18][19][20][21] This methodology utilizes reducing and capping agents to reduce Pd cations and stabilize the formed nanoparticles. The resulting PdNP structure and size can be manipulated by adjusting the reagents' pH, temperature, and concentration.…”

“…However, this method is still limited from an applicative point of view due to the chemical stability of the particles. [19][20][21] In addition, chemical capping and reduction agents oen involve toxic and environmentally unfriendly materials, resulting in considerable amounts of toxic waste.…”

Hydrogen Trapping in Palladium Nanoparticles Revealed by Electrochemical, X-ray Scattering, and Spectrometric Measurements

“…This unique property makes Pd and its alloys attractive materials for several applications, including hydrogen storage, 1 separation and purification, 2,3 sensing, 4,5 and (electro)catalysis. 6,7 H atoms can be inserted into Pd by applying a H 2 pressure. The α phase (PdH x -α), corresponding to a PdH x solid solution with slightly expanded lattice constant, first forms at low H 2 pressure (<0.01 atm).…”

“…Due to the unique ability of palladium (Pd) to reversibly insert (absorb) and de-insert (desorb) large quantities of hydrogen (H) at room temperature and low pressure, the palladium–hydrogen (Pd–H) system has been widely studied. This unique property makes Pd and its alloys attractive materials for several applications, including hydrogen storage, separation and purification, , sensing, , and (electro)­catalysis. , H atoms can be inserted into Pd by applying a H 2 pressure. The α phase (PdH x -α), corresponding to a PdH x solid solution with slightly expanded lattice constant, first forms at low H 2 pressure (<0.01 atm).…”