As a catalytic center, the 4N-coordinated
post-transition
metal
(PM) confined within phthalocyanine (Pc) shows promise for the environmentally
friendly synthesis of CH4 and NH3. A range of
PM–Pc catalysts (where PM represents Al, Ga, In, Tl, Ge, Sn,
Pb, and Bi) is methodically evaluated through DFT mechanistic analysis
and electrochemical exploration to determine their stability, activity,
and selectivity. Our comparative analysis reveals that the orientational
specificity of initial cyanide adsorption would play a crucial role
in cyanide electroreduction reaction (CNRR) pathways within diverse
PM–Pc nanosheets. Specifically, the NC* model typically requires
higher supplies of Gibbs free energy for the CNRR, preponderantly
resulting in CH3NH2. Conversely, the counterpart
of the CN* model necessitates lower energetic demands, leading to
a broader diversity of products including methane and ammonia. Of
particular significance that the relationships of limiting potentials
(U
L) through two types of descriptors,
ΔG
NC*→HNC* and ΔG
CN*→HCN*, were essential for constructing
volcano plots, thus illustrating the relation within the intrinsic
adsorption performance of diverse PM–Pc series and their associated
prominent CNRR efficiency. From a comprehensive screening of the studied
results, we have determined that the nanosheets Al–Pc, In–Pc,
Ge–Pc, and Sn–Pc (triggered by the CN* model) are the
exceptionally proficient electrocatalysts, specifically in producing
only CH4 and NH3 via the CNRR process, as indicated
by our final compiled findings. Within the range of nanosheets evaluated,
the Al–Pc associated model emerges as a standout, demonstrating
markedly higher selectivity and CNRR activity than its counterparts.
This study advances the understanding of the unique superior characteristics
of SACs, subsequently providing innovative perspectives that could
directly guide their discovery for CNRR applications.