General Synthesis of Amorphous PdM (M = Cu, Fe, Co, Ni) Alloy Nanowires for Boosting HCOOH Dehydrogenation

Abstract

Noble metal-based nanomaterials with amorphous structures are promising candidates for developing efficient electrocatalysts. However, their synthesis remains a significant challenge, especially under mild conditions. In this paper, we report a general strategy for preparing amorphous PdM nanowires (a-PdM NWs, M = Fe, Co, Ni, and Cu) at low temperatures by exploiting glassy non-noble metal (M) nuclei generated by special ligand adsorption as the amorphization dictator. When evaluated as electrocatalysts toward formic acid oxidation, a-PdCu NWs can deliver the mass and specific activities as high as 2.93 A/mg Pd and 5.33 mA/cm 2 , respectively; these are the highest values for PdCubased catalysts reported thus far, far surpassing the crystalline-dominant counterparts and commercial Pd/C. Theoretical calculations suggest that the outstanding catalytic performance of a-PdCu NWs arises from the amorphization-induced high surface reactivity, which can efficiently activate the chemically stable C−H bond and thereby significantly facilitate the dissociation of HCOOH.

Amorphous-crystalline PdRu bimetallene for efficient hydrogen evolution electrocatalysis

“…15 In general, amorphous catalysts with a metastable state possess unsaturated active sites on the surface, resulting in improved activity and stability. 16,17 Heterophase engineering, in particular, the formation of an amorphous-crystalline heterophase, is an attractive approach to enhance electrocatalytic activity due to unique physicochemical properties. 18,19 However, strong metallic bonds of noble metals cause difficulty in the preparation of amorphous noble metal electrocatalysts.…”

Synergistic Strategy for the Fast Dehydrogenation of Liquid Organic Hydrogen Carriers over a Pd/MoO3 Catalyst

“…Usually, the conversion from 4H-NEC to NEC is the rate-limiting step; this is the reason why the dehydrogenation rate slows down in the later stage of the reaction. , Notably, compared to the Pd/Al 2 O 3 catalyst (Figure S5f), the conversion rate from PNEC to 8H-NEC is extremely fast on Pd/MoO 3 catalysts (Figure S5a–e), no matter how much the Pd loading is. This may be explained by the readily H spillover from Pd to MoO 3 , − which would provide more active sites for the PNEC to adsorb and C–H bond activation on Pd.…”

“…Therefore, we propose an alternative strategy to accelerate the dehydrogenation process of LOHCs. The active sites of traditional noble metal catalysts not only need adsorb reactants to break C–H bonds, but also need adsorb H atoms to form H 2 molecules for desorption. , This somehow hinders the continuous adsorption of reactants because the active sites are occupied by massive H atoms, resulting in a slow dehydrogenation rate. Nevertheless, MoO 3 can quickly receive the H atoms from noble metal to form H x MoO 3 , , this could provide more active sites for the adsorption of the reactants on active metal.…”

Tailoring Amorphous PdCu Nanostructures for Efficient C–C Cleavage in Ethanol Electrooxidation

“…Considering that the atomic structure of noble metal products in a wet-chemical synthesis is predetermined from the birth of the nucleus, , we recently achieved the amorphization of noble metals by exploiting glassy nucleation rather than conventional crystalline nucleation to initiate the growth in solution phase . In a delicately designed oleylamine-ascorbic acid (OAm-AA) system where the nucleation of non-noble metals (M) was prior to that of Pd, we found that once the M nucleus was made into an amorphous structure (easy to achieve due to its weak metallic bonding), their subsequent galvanic replacement with Pd precursors could replicate the amorphous structure to the final products.…”

“…A long-existing obstacle restricting the kinetics of EOR has been the unsatisfactory C–C bond cleavage efficiency, which generally leads to predominant C2 products (CH 3 COOH and CH 3 CHO) over C1 products and thus inefficient energy conversion. − Endowed with the enriched coordination-unsaturated surface sites, amorphous nanocatalysts have been demonstrated capable of activating inert chemical bonds, such as NN, CO, and CH. ,− Likewise, we believe the chemically stable C–C bond can also be efficiently cleaved on the amorphous surface, especially considering the high current density achieved by a-PdCu spheres toward EOR. To confirm this, we employed high-performance liquid chromatography (HPLC) to analyze the final products, which were collected by operating the EOR catalysis at a constant potential of −0.15 V versus Hg/HgO until the electric quantity accumulated to 50 C. As shown in Figure S15, a-PdCu nanospheres exhibited a rather lower C2 selectivity than Pd/C and c-PdCu nanospheres.…”