Nanosheet array-like Cu@Cu2O-CuNiAl(O)/rGO composites for highly efficient reduction of nitrophenol: Electronic and structure promotion effect of nickel

Controllable Synthesis of Cobalt-Containing Nanosheet Array-Like Ternary CuCoAl-LDH/rGO Hybrids To Boost the Catalytic Efficiency for 4-Nitrophenol Reduction

“…The Cu 1.5 Co 1.5 Al-LDH/rGO hybrid is considered to be the more desirable catalyst based on the comprehensive analysis of the reaction rate and the active Cu content, which shows markedly improved catalytic activity compared with Cu 1 Ni 2 Al-LDH/rGO and Cu 1 Mg 2 Al-LDH/rGO previously reported by our group, indicating that the doping of an appropriate amount of Co 2+ species substantially increases the activity of Cu species and strengthens the possible bi-transition-metal synergistic effect between Cu and Co species. Moreover, Cu 1.5 Co 1.5 Al-LDH/rGO has excellent catalytic activity compared with the recently reported Cu-related catalyst, even comparable to some noble ones. ,,,,, …”

“…Moreover, the apparent activation energy ( E a ), activation enthalpy (ΔH # ), entropy (ΔS # ) and Gibbs free energy (ΔG # ) of catalytic reduction process were determined using eqs . The E a value for the reduction of 4-NP over Cu 1.5 Co 1.5 Al-LDH/rGO is 20.7 kJ mol –1 from the ln­( k app ) versus 1/ T (Figure C), indicating that the 4-NP reduction occurs on the catalyst surface. , The obtained E a value is lower than most composites in the literature (Table ), further indicating that the present hybrids have higher catalytic activity. The ΔH # and ΔS # values of 17.9 kJ mol –1 and −151.8 J mol –1 K –1 , respectively, are obtained in the ln­( k app / T ) against 1/ T (Figure D), indicating that the reduction of 4-NP is a endothermic process, entropically unfavorable, and requires a catalyst .…”

Hierarchical-Structured Pd Nanoclusters Catalysts x-PdNCs/CoAl(O)/rGO-T by the Captopril-Capped Pd Cluster Precursor Method for the Highly Efficient 4-Nitrophenol Reduction

“…According to the plot of ln­( k app ) versus 1/ T (Figure C), the E a value for 4-NP reduction over 0.17-PdNCs/CoAl­(O)/rGO-300 was calculated to be 19.19 kJ mol –1 , indicating that the 4-NP reduction occurred on the catalyst surface. , The lower E a value (Table S3) means the more activated reactant, along with more opportunities for effective collisions, leading to a higher reaction rate . The Δ H # and Δ S # values obtained from the plot of ln­( k app / T ) versus 1/ T (Figure D) are 16.70 kJ·mol –1 and −212.4 kJ·mol –1 ·K –1 , respectively, suggesting that the 4-NP reduction is an endothermic process, entropically unfavorable and the catalysts are urgently needed .…”

“…The reduction of 4-NP to 4-AP has been extensively studied as a commonly employed model reaction to evaluate the activity of various nanostructured catalysts . The present catalysts x -PdNCs/CoAl­(O)/rGO- T can be applied for the 4-NP reduction in the existence of excessive NaBH 4 .…”

“…The Δ H # and Δ S # values obtained from the plot of ln­( k app / T ) versus 1/ T (Figure D) are 16.70 kJ·mol –1 and −212.4 kJ·mol –1 ·K –1 , respectively, suggesting that the 4-NP reduction is an endothermic process, entropically unfavorable and the catalysts are urgently needed . In addition, assuming that the activation parameters are associated with the most crucial activation step in the mechanism of 4-NP reduction, it can be considered that the positive value of Δ H # and the negative value of Δ S # indicate the presence of a transition state. , …”