I have changed your code. You can plot the variables you want now. You need to read about linspace, element by element operations and plot.
m = 100 ;
%Base Conditions
a_anode = 0.54;%Anodic transfer coefficient
a_cathode = 0.52;%cathodic transfer coefficient
T = 300; %Cell Temperature
S_anode = 3.5e-3;%Reference kinetic parameter(anode)(A/cm^3)
S_cathode = 1.95e5;%Reference kinetic parameter(cathode)(A/cm^3)
C_oxygen_ref = 1.95e5;%Reference kinetic parameter(cathode)(A/cm^3)
% C_oxygen_f = 0.0018; %Feed oxygen concentration(mol/cm^3)
C_oxygen_f = linspace(9e-3,30e-3,m) ;
Y_G = 0.5; %Glucose concentration parameter
Y_O2 = 1; %oxygen concentration parameter
B = 0.5; %Hydroxyl ions concentration parameter
L_c = 0.002;%Catalyst layer thickness(cm)
L_d = 0.035;%Diffusion layer thickness(cm)
L_m = 0.0055;%AEM electrolyte thickness(cm)
% C_glucose_f = 0.0003; %Feed glucose concentration(mol/cm^3)
C_glucose_f = linspace(3e-3,10e-3,m) ;
C_glucose_ref = 0.0001; %Reference glucose concentration(mol/cm^3)
C_KOH_f = 0.001; %Feed KOH concentration(mol/cm^3)
C_KOH_ref = 0.001; %Reference KOH concentration(mol/cm^3)
E_d = 0.78; %void fraction of the diffusion layer
D_glucose_d = 6.5e-6; %Diffusion coefficient of glucose in KOH(cm^2/s)
D_glucose_f = 6.5e-6; %Diffusion coefficient of glucose in fumion(cm^2/s)
k_w = 1e-10; %Hydraulic permeabilty(cm^2)
u_w = 0.000899; %visocsity of water(Pa-s)
Delta_P = 1200; %Pressure difference across diffusion layer(Pa)
E_s = 0.32; %Volume fraction of solid phase(Pt-Bi/C) in catalyst layer
E_m_anode = 0.08; %Volume fraction of the ionomer in catalyst layer
K_m = 0.008; %Conductivity in OH form in H2O at T=25C(Scm^-1)
K_s = 8.131e5; %Electronic conductivity of solid phase in catalyst layer(Scm)
R_in = 2.6; %Internal resistance of the cell(ohms)
A = 0.75; %geometric area(cm^2)
n_H2O = 2.3; %Electroomsmotic drag coeeficient
P_O2 = 0.5; %oxygen side pressure(atm)
K_O2 = 3.078e5; %O2 Henry's constant(atmcm^3mol^-1)
D_O2 = 0.0056;%Diffusion coefficient of the oxygen in plain medium(cm^2/sec)
E_m_cathode = 0.2; %Volume fraction of the ionomer phase in catalyst layer
E_c =0.6; %Void fraction of the catalyst layer
R = 8.314;%Gas constant
F = 96485;%Faraday constant
I = 0.53e-3;%Current density of fuel cell
n_anode = 2;%number of exchange protons per mole of reactant(glucose)
n_cathode = 4; %number of exchange protons per mole of reactant(anode)
I_l = 1;
E_v = 1.3;
%-------------------------------------------------------------------------
%Activation overpotential
%Anode
%Exchange currenty density
i_O_anode = S_anode *((C_glucose_f./C_glucose_ref)).^0.5 ;
%Activation overpotential at anode
V_act_anode = ((R*T)/(n_anode*F*a_anode))*log(I./i_O_anode);
%Cathode
i_O_cathode = S_cathode *((C_oxygen_f./C_oxygen_ref)).^0.5 ;
%Activation overpotential at cathode
V_act_cathode = ((R*T)/(n_cathode*F*a_anode))*log(I./i_O_cathode);
%Total activation overpotential
V_act = V_act_cathode + V_act_anode;
%Ohmic Overpotetntial
V_ohmic = I * A * R_in ;
%Concentration overpotential
%Anode
V_conc_anode = ((R*T)/(n_anode*F))*log(1-(I/I_l));
%Cathode
V_conc_cathode = ((R*T)/(n_cathode*F))*log(1-(I/I_l));
%Total concentration overpotential
V_conc = V_conc_cathode + V_conc_anode;
%Real output voltage of cell
V_cell = E_v - V_act - V_ohmic - V_conc;
%Power of fuel cell
P = V_cell * I;
%--------------------------------------------------------------------------
%Plots
%Polarization curve: Cell Potential vs Current density
plot(P) % Put your variables here
