**3.5 Highly dispersed ultra-small Pd nanoparticles on gadolinium hydroxide nanorods for efficient hydrogenation reaction**

Heterogeneous synergist hydrogenation responses are vital to the petrochemical business and fine compound blend. In this, we present the primary case of gadolinium hydroxide [Gd(OH)3] nanorods as a help for stacking ultra-little Pd nanoparticles for hydrogenation responses. Gd(OH)3 has an enormous number of hydroxyl bunches superficially, which go about as a perfect help for good scattering of Pd nanoparticles.

**Figure 12.** *General procedure for synthesis of 2-substituted benzimidazoles.*

Gd(OH)3 nanorods are set up by aqueous treatment, and Pd/Gd(OH)3 impetus with a low stacking of 0.95 wt % Pd is acquired by photochemical testimony. The synergist hydrogenation of *p*-nitrophenol (4-NP) to *p*-aminophenol (4-AP) and styrene to ethylbenzene is executed as a model response. The acquired Pd/Gd(OH)3 impetus shows amazing action when contrasted with other detailed heterogeneous impetuses. The rate consistent of 4-NP decrease is estimated to be 0.047 s<sup>−</sup><sup>1</sup> and the Pd/Gd(OH)3 nanocatalyst demonstrates no stamped loss of action even after 10 back to back cycles. Also, the hydrogenation of styrene to ethylbenzene over Pd/Gd(OH)3 nanorods shows a turnover recurrence (TOF) as high as 6159 h<sup>−</sup><sup>1</sup> with 100% selectivity. Besides, the impetus can be recuperated by centrifugation and reused for up to 5 back to back cycles without clear loss of movement. The outcomes show that Gd(OH)3 nanorods go about as an advertiser to upgrade the reactant action by giving a synergistic impact from the solid metal help communication and the huge surface region for high scattering of little estimated Pd nanoparticles advanced with hydroxyl bunches superficially. The elite of Pd/Gd(OH)3 in heterogeneous catalysis offers another, effective and effortless methodology to investigate other metal hydroxides or oxides as backings for natural changes (**Figure 13**) [19].
