urxvt not handling UTF-8 when started from i3 commands

Steps:

1. Start i3. (config below)
2. Press alt-Enter.
3. ls the home directory:

fam@localhost:~$ ls
bin  downloads  myhome  æµè¯

1. The 4th item is in Chinese, but it's not displayed correctly.
2. Start another urxvt window by pressing alt-d (dmenu) and type urxvt.
3. ls in new window, get the same result with previous.
4. Start another urxvt from command line (after either of the incorrect ls) by

fam@localhost:~$ urxvt

1. This time a "good" version of urxvt is running ls will get the right result.

fam@localhost:~$ ls
bin  downloads  myhome  测试

Appearance: any urxvt opened by alt-enter or dmenu, or started from i3 config file (exec urxvt) fails to display UTF-8 character. But one started from terminal works just fine.

No such problem with Terminator.

My i3 config

# This file has been auto-generated by i3-config-wizard(1).
# It will not be overwritten, so edit it as you like.
#
# Should you change your keyboard layout somewhen, delete
# this file and re-run i3-config-wizard(1).
#

set $mod Mod1

# Font for window titles. Will also be used by the bar unless a different font
# is used in the bar {} block below. ISO 10646 = Unicode
# font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
# The font above is very space-efficient, that is, it looks good, sharp and
# clear in small sizes. However, if you need a lot of unicode glyphs or
# right-to-left text rendering, you should instead use pango for rendering and
# chose a FreeType font, such as:
font xft:Droid Sans 11

# Use Mouse+$mod to drag floating windows to their wanted position
floating_modifier $mod

# start a terminal
bindsym $mod+Return exec urxvt

# kill focused window
bindsym $mod+Shift+q kill

# start dmenu (a program launcher)
bindsym $mod+d exec dmenu_run
# There also is the (new) i3-dmenu-desktop which only displays applications
# shipping a .desktop file. It is a wrapper around dmenu, so you need that
# installed.
# bindsym $mod+d exec --no-startup-id i3-dmenu-desktop

# change focus
bindsym $mod+h focus left
bindsym $mod+j focus down
bindsym $mod+k focus up
bindsym $mod+l focus right

# alternatively, you can use the cursor keys:
bindsym $mod+Left focus left
bindsym $mod+Down focus down
bindsym $mod+Up focus up
bindsym $mod+Right focus right

# move focused window
bindsym $mod+Shift+h move left
bindsym $mod+Shift+j move down
bindsym $mod+Shift+k move up
bindsym $mod+Shift+l move right

# alternatively, you can use the cursor keys:
bindsym $mod+Shift+Left move left
bindsym $mod+Shift+Down move down
bindsym $mod+Shift+Up move up
bindsym $mod+Shift+Right move right

# split in horizontal orientation
bindsym $mod+g split h

# split in vertical orientation
bindsym $mod+v split v

# enter fullscreen mode for the focused container
bindsym $mod+f fullscreen

# change container layout (stacked, tabbed, toggle split)
bindsym $mod+s layout stacking
bindsym $mod+w layout tabbed
bindsym $mod+e layout toggle split

# toggle tiling / floating
bindsym $mod+Shift+space floating toggle

# change focus between tiling / floating windows
bindsym $mod+space focus mode_toggle

# focus the parent container
bindsym $mod+a focus parent

# focus the child container ...